I thought it would be interesting to see if hot glue could be used in thin sheet form, and if so, could I do marbling with those colored hot glue sticks?

This is my experiment and my conclusion is that it is possible! And it actually works rather well.

I learned so much during this process, and given that it was an experiment (meaning I was just making stuff up as I went along), I had to go through the process multiple times because I kept messing up and also kept thinking of better ways of doing things and different things to try.

Subsequently, this Instructable has multiple parts that I've had trouble figuring out how to put in the best order.

So, here is how it is ordered so you can skip to the part(s) in which you are most interested:

Step 1 General Supplies and Equipment

Step 2-4 Preparing Thin Glue Stick Sheets

Step 5-6 Making Tools for Marbling

Step 7-8 Marbling with Hot Glue

Step 9 Additional Oven Melting Ideas

Step 10-12 Assembling the Zipper Pouch

Step 13-15 Assembling the Gold Card Holder

Step 16-19 Problems, Accidents, and How to Solve Them

Step 20 Thoughts for Future Experiments

Step 1: Supplies and Equipment

Gold Glitter Card Case

Glue Sticks
Glitter
Parchment Paper (Not wax paper. Parchment is coated with silicone.)
Scissors
Paintbrush
Iron
Velcro Dots
Silicon Mold and Black Glue Stick (Optional)
Glue Gun

Marbled Stationary Pouch

Glue Sticks
Colored Glue Sticks
Parchment Paper
Paper Clips (4)
Scissors
Iron
Oven
Baking Sheet
Zipper
Glue Gun

Extras

Cutting Mat and Rotary Cutter
Heat Tool

Step 2: Melting Glue Sticks With Iron

I laid 3 to 8 mini glue sticks between a large folded sheet of parchment paper and then ironed it on high. As it melted, I worked it kind of like rolling dough. Once I could see that it was spread out well, I either left it to cool, or put it in the freezer to speed the process along. Once it is cool, it peels right off.

If doing the marbling, you'll want to do multiple colors. I also used clear glue sticks for the base of the marbling because the are cheaper. They also work for transparent sections.

Step 3: Making the Glittered Sheets

First, I made 2 clear sheets (see previous step). I brushed glitter onto one clear sheet, and then topped it with the other clear sheet. I then ironed the sheets together. I found that it had too many air bubbles, so I cut it in half, stacked them, and then ironed again. This laminating method works well, and the second stacking and ironing gave the glitter depth.

Tip: After you peel it off, it will look rather matte. You can bring out the shine again by gently and quickly heating the surface with a heat gun.

Step 4: Prepping the Colored Glue Sticks for Marbling

I prepared multiple sheets of clear and colored. The first batch I made, I just cut with scissors, but the second batch, I decided to first cut into the size of the marbling tray before stripping them to get uniform coverage of the baking tray. I also hole punched some dots. I recommend saving all your scraps, you can either remelt them, or use them for future designs.

Step 5: Prep the Parchment

If you are doing marbling, you will need a tray for baking. I made mine out of parchment paper.

Pictures Show finished product first and then assembly steps

Cut out a 8"x12" rectangle
Fold each side up 1"
Cut one fold of each corner from edge to fold intersection
Folding the resulting tabs to the outside, paperclip them to the sides of the main body (I recommend the long side of the paperclip to the outside and the short to the inside).

Note: I've since realized a better method for making the tray. Instead of cutting to create a tab, fold a diagonal line from each corner to its respective fold intersection. This should result in a triangle that can be folded against the side and secured with a paperclip. While I've not tried it, I believe it is the superior method, as it will not leak (though leaking was not actually a problem for me).

Step 6: Make a Marbling Comb

There is only a short window to work with the rapidly cooling and solidifying hot glue, and after running into issues while using only one stick, I realized multiple parallel sticks would not only be faster, but give uniform lines.

Cover a ruler with masking tape (I recommend not covering the scale markings, as these will help you space your toothpicks evenly.
Using a glue gun, run a line of glue down the masking tape perpendicular to the straight edge of the ruler
Apply a tooth pick while still hot
Repeat, spacing the toothpicks evenly down the ruler*

*Make sure that the bottom of the toothpicks all line up. You can check this by placing the teeth perpendicular to a flat surface. I didn't do this and only eye balled it, and so when I used the comb, sections didn't marble properly because some of the teeth were too short to engage the hot glue.

Step 7: Layout and Bake the Hot Glue Strips

To prepare a sheet of marbled hot glue, I put my parchment tray on a baking tray, and then laid down a thin sheet of clear hot glue. After that, I created a stripped design of alternating colors. When satisfied with the design, I placed it into a preheated 400-420 degree F oven for 2-4 minutes until it was melted.

Step 8: YAY! Marble

When the hot glue is good and melted, carefully remove it from the oven
Insert the tips of the comb (or stick) into the hot glue
Drag the tips through the glue to create a design
Consider going back through in the opposite direction
Work fast! The glue solidifies rather quickly. If this happens, you can put it back in the oven to get it hot again to give you some more work time, but be forewarned, if you do this too much, your design can warp and it can make your lines not as crisp.
Put it back in the oven for a few minutes until the little valleys created by the sticks disappear and become even
Carefully remove it from the oven, and let it cool
Peel the marbled glue sheet from the parchment tray

Note: As seen in the video, if using a comb, make sure all the teeth are even, or you with get sections that don't engage the glue!

Step 9: Layout Ideas

I used cookie cutters as an impromptu stencil for glittering the surface. I then placed it in the oven for a few minutes to let the glitter melt into the glue.
Using dots and strips I made a starburst design. I had originally intended to marble a spiral in the design, but then chickened out at the last moment.
Using random scraps, I layered up this design, and this time I did marble concentric hearts when it came out of the oven.

Step 10: Marbled Pouch: Installing the Zipper

I found it helpful to tape the zipper down so it won't be moving around. (I didn't do this the first time and it was a symphony of "ouch!" and curse words as I kept burning myself with the hot glue).
Trim the top edges of the glue sheets just enough so they are smooth and even.
Run a thin ribbon of hot glue from a glue gun down the length of the zipper.
Carefully line up the hot glue panel, and then press the edge into the hot glue. A silicone spatula can be very handy for pressing the panel into the hot glue without burning your fingers. Also, make sure the shiny right side is facing up. I wasn't paying attention and glued my shiny side down, so now the right side is on the inside of the bag! Grrrr!!! In my defense, I'm doing a multi-day water only fast and am a bit dingy.
Repeat the process with the other panel, making sure it lines up well with the first panel.

Step 11: Marbled Pouch: Trim It Down

Fold the panels over on each other, making sure to line the edges up carefully.
Trim off the excess and uneven edges of all 3 non-zippered sides.

Step 12: Melt the Edges

I tried many methods of melting the edges together (iron, heat gun, glue gun tip, and heat burning tool), and to be honest, I'm still not completely satisfied with the results. It was also impossible to take photos of the process because you need both hands, and because it is hot with a short cooling time, I couldn't just sit there posed with the timer function with out messing things up. So without pictures, here is the general idea:

Cover the edge with parchment paper
Using a source of heat, either run the heat over the edge, or run the edge over the heat.
Also consider laying it flat and running the heat source a few millimeters in from the edge.
While it is still warm, press the edges together, and use the folded parchment to create a smooth rounded edge.
Best of Luck! Sometimes it takes multiple tries. I think it is better to do a little bit multiple times than to get over zealous and end up melting too much and then warp the panels and design.

Step 13: Glitter Card Holder: Cut It Out

To make the card holder, I laid down some cards to eye the dimensions. I cut a rectangle 4" x 8". I then proceeded to use 2 different sized cups to make the rounded edges; one for the flap that comes down (at least a 4" diameter cup) and one for the indent to make accessing the cards easier.

Step 14: Glitter Card Holder: Sealing the Edges

I folded the holder into shape and then held it between to cards to stabilize it, only allowing the just a few millimeters of the edge to be exposed. I then covered the iron surface with parchment, and quickly ran the edge over the hot surface. I then repeated this on the other side.

Step 15: Glitter Card Holder: Finishing Touches

I created a bow using a silicone mold. It is easy, just squeeze the hot glue from the gun into the mold, let it cool, and then pop it out. Trim any yucky bits and then I gently went over it with the heat gun just to return the shine.
Using the glue gun, I put a few dots of glue on the back of the bow and then positioned it on the envelope flap.
Finally, I glued a set of Velcro dots to the envelope to secure the cover.

Step 16: Oops!

I ruined my ironing board and melted a bunch of gunk to onto the surface of my iron.

Lessons learned:

Make sure the parchment sheets used for ironing are much larger than you think you will need. I thought mine were big enough, but glue escaped and left irremovable globs on the board.
Make sure all the glitter is between the sheets of parchment. If any glitter escapes, it can melt onto the iron (notice all the tiny dots.)

Step 17: Problems to Avoid

I thought it would be a good idea to create a stenciled zone to guide the glue into while ironing. While theoretically it was a good idea, in practice the sharpie ink burned into the hot ironed hot glue. Thinking oops, I just need to make sure the ink is facing down and not on the glue surface, I then faintly ironed the rectangle into my ironing board. Maybe a colored paper rectangle under both layers of parchment is the answer???

Step 18: Curse of the Bubbles!

Ahhh, dealing with bubbles was a constant battle during this process. They rise to the surface and then pop, and when they pop they leave a void. I tried using a stick to pop them, and then swirl the molten glue around to heal them, but when the sheets are thin, it is very difficult. With thicker sheets it is not so much a problem, but then it is too thick for the applications I had in mind.

Step 19: Bubble Fixes

Add more of the matching colored material
Swirl and pop with stick (only works on the smallest bubbles and holes)
Add more material with a hot glue gun

In all these scenarios, you will need to put it back into the oven for a few minutes to fuse and melt together.

Step 20: Thank You & Thoughts for Future Experiments

Thanks for reading this far!

I have some ideas for other things to do with the thin sheets:

Cut them into shapes and then use them as appliques
Use them as non-skid traction devises
Cut and roll it into a tassel as a decorative zipper pull for the pouches

Additional Thoughts:

Could you set the parchment tray on a griddle to have a constant source of heat to give indefinite working time for marbling?

If you have any application ideas or suggestions for improved technique I'd love to know, and I'll add them to the list. After days of experimenting, I need to take a break and do some adulting, but maybe I'll comeback to it again in the future and give them a try. : )

Introduction: Marbled Hot Glue