Here's a whimsical bit of colour for a window.

I made a 1-level shelf and liked it so much that I then made a 2-level version out of wood I had left over from the first one.

For the art historians: I was inspired to make this by the baby food jar screw organizers that my father mounted in his workshop. He had many, many jars attached to the bottom of shelves and even had a couple of 2"x2" boards that rotated with jars affixed to the four sides. Here's an instructable using jam jars that captures the idea a bit. Given that Dad used these organizers for about 50 years, I'd say he found them to be useful.

Warning based on my experience - if you want to put a shelf together with the jars and the marbles and then carry it to different places in your house to see how it looks, put it all in some sort of container. Because if you just carry it around, the vibration might cause a jar to loosen from its lid, drop to the floor, smash into pieces and send broken glass and marbles all over the place.

Supplies

For the one-level shelf, I used:

a piece of 1/2" x 3" scrap wood cut to 15" in length (I'm not super precise in measuring and my cuts were a bit crooked, but you don't notice this on the finished shelves)
eight 3/4" cup hooks
about 12' of chain
four small jam jars of different sizes and one tiny ketchup bottle
a bunch of coloured marbles
five 3/4" wood screws (but if I did this again, I'd use 10 screws)
black spray paint
a toy dinosaur
some paper

For the two-level shelf, I used:

a piece of 1/2" x 3" scrap wood cut to 15" in length
a piece of 1/2" x 3" scrap wood cut to 7" in length
sixteen 3/4" cup hooks
about 8' of chain
five small jam jars of different sizes and one skinny hot saucebottle
a bunch of coloured marbles, a couple of skinny clear lightbulbs, and a clear glass tube
twelve 3/4" wood screws
black spray paint
a bunch of little toy dinosaurs from a dollar store
some paper

Step 1: Painting

Before painting, drill holes in the jar lids with a 3/32" drill bit. (For my first shelf, I only drilled one hole in each lid. But when I screwed the jars on to the lids, the lids rotated. For the second shelf, I drilled two holes in each lid. Which meant I had to use twice as many screws, but no lid rotation when attaching the jars.)

I painted everything black because I thought having them that would give more emphasis to the colours of the marbles. I used spray paint I had in the basement for most of it, with acrylic from the craft cupboard for touch ups.

For the painting, I learned after my first try that putting a screw through a hole in the lids allowed me to move the lids around without touching the painted lids and also minimized how much of the lids touched the cardboard while the paint dried.

Step 2: Attach the Jar Lids to the Bottom of the Shelf

Arrange the lids on the bottom of the shelf in the order for the jars to go.
Temporarily tape the lids to the shelf so you'll know where to make the drill holes.
Use a pencil to mark where to drill the wood for each lid.
Tape the drill bit so that only about 3/8" of the bit shows.
Drill holes for the lids.
Attach the lids with 1/2" or 3/4" wood screws.

Step 3: Hang the Shelf

Cut a piece of paper to match the exact size of the top of the shelf, tape it in place, and write "top" on the paper.
Mark spots for the cup hooks on the top of the shelf at each corner, roughly 1/2 inch in from the sides.
Use the 3/32" drill bit, still with the tape on it, to drill four holes for the cup hooks .
Carefully remove the paper from the shelf.
Screw the black cuphooks into the wood.
Making sure the bottom of the paper is down, tape the paper to the top of the window frame exactly above where the shelf is to hang.
Drill holes in the spots on the paper that show where the cuphooks should be with the same drill bit you used for all the other holes
Screw the unpainted cuphooks into the window frame (for our window frames, the bronze colour of the cuphooks is a better match than black would have been).
Hang the chain from the top down to where you want the shelf to hang.
Using some tape to mark the length, very carefully make four exactly identically long pieces of chain.
Hang the four pieces of chain from the top hooks.
Hang the shelf so the jar lids are on the bottom.
And if you're doing a 2-level shelf - do all this to hang the second shelf from the first shelf.

Step 4: Marbleize the Shelf

Clean labels off the jars with soapy water or Goo Gone.
Fill the jars with marbles using either a random method or an artistic design that suits your aesthetic.
If you have a wide jar, you might do well to put a skinny light bulb in with the marbles to increase the light flow.
Screw the jars into their corresponding lids

Step 5: Use the Shelf?

You don't actually have to use this as a shelf. You could consider it to be its own art.
But they look great with little succulents.
To prevent plants from falling off, it might help to affix a jar lid to the top with something sticky.
Because the shelf sways a bit.
For this reason, a plastic dinosaur is the perfect thing to put on the shelf.
1. If the dinosaur falls, there will be no mess or destruction.
2. It's not easy to find places to display your plastic dinosaurs.