The idea for this costume came because I was trying to google pregnancy costumes that were good for work. The google results were mostly people who painted their bellies and left it out, NOT good for work. Aside, my belly doesn't seem to want to grow :(
So, I thought and thought and said to myself "Hey I can make an Oven and then it will be Bun in the Oven!" And thus this costume and instructable came about.

Materials:
6 pieces of foam board
Hot glue / Hot Glue Gun
Sharpie Markers
Gel Pens
Paint
Metal Gate
4 Brads
5 Buttons
Exacto Knife
Cellophane
String

Step 1: Cut the Foam Board

To make sure this costume was not too heavy to go over my lifting restrictions I made this costume out of foam board and did NOT paint the board. I got white foam board and left it white. To put the costume together, I made indentations one one piece and on the connecting piece and slits to match on the piece it connected to. I used an exacto knife to cut all the slits out. Each of the four sides started with one side slit and one side indents so that they would connect to each other. Be careful when making the slits and make sure to label the pieces so that they match when you put it together. My last one was cut too fast (Excitement that it was working so well) and the slits / indents were slightly off. I found the best way to get them to make sure they matched was to make the indents (i made them 2 inches wide then 2 inch gap) then put the indents along the edge of the board it will connect to and mark where the slits slits are lined up to. Then I used the first one as a template for the others.
After making the four bottom foam board pieces and marking which is which (I marked both which side is up with an arrow and Left, Right, Front, Back) they "snapped" together. I just made sure I was able to fit inside with room to grow (I started this in the beginning of September and Halloween is in the end of October so in case the belly grows I want there to be some room)

Step 2: Make the Stove Top

For the stove top, I took the Front, Left, and Right pieces and made additional indents. These slits were made so that they left enough room in front of me to fit into once the top piece was on. The indents were on the top end of the board. Then on the last foam board, I made slits on three sides to match the indents and the stove top was able to sit right on top of the oven. I went inside to make sure I fit with the stove top on.

Step 3: Make the Oven Front

As you probably know, the stove top has that extra lip for all the buttons and timers. To make this I made another set of slits on the stove top and made a smaller piece with indents to slip into it. I made the slits the same two inches deep and then would eventually cut the board so that it wasn't too tall to block myself. I wanted to make my details first to make sure they fit. (Next step)

Step 4: Make the Stove Top Details

So, I never realized how much detail was in a stove top until I started making this costume.

First, there are the stove top grates. To make these:

In the back yard there was one of those small metal garden gates that was falling apart. We snipped off long pieces of the gate.
I rolled the strips of the metal garden gate into spirals.First
First I tried painting the spirals, this did not work too well.
I dipped the spirals into paint and let them dry. This worked much better. (Very messy step make sure to use paint that is able to be washed off with water)

Then there are the buttons. To make these:
1. I cut small pieces of foam into squares approximately 1 inch by 1 inch
2. I used a black sharpie marker to make them black so they stick out on the white stove top.
3. I used a Green Gel pen to mark the labels
And the knobs. To make these:
1. I found four black buttons again about 1inch in diameter.
2. Then I cut four pieces of foam board to look like the knob handle.
3. I used the black sharpie to make the handles black.
4. I hot glued the two pieces together.
And the clock. To make these:
1. I picked numbers that had straight edges since I would be cutting with an exacto knife.
2. I drew the numbers in block letters.
3. Cut the numbers out with the exacto knife
4. Last, I used a marker to make them green.
Put the back panel together. To do this:
1. I cut a piece of foam board so that the buttons and clock would fit.
2. I placed the pieces so the clock was in the middle and the buttons were on each side.
3. Then I glued the pieces onto the board.
Put the knobs on. To do this:
1. I made a small hole with a pen to fit a brad in.
2. I glued the knobs onto a brad with hot glue.
3. I put the piece through the holes and closed the brad so that it would spin.

Then I cut the panel down to size and gave it some color (black paint) to make it stand out a little more.

Step 5: Make the Oven Front

On the front of the oven I cut the front to make two sides and a top and scored the bottom of a square in the center. Next, I cut a full square out in the center of this piece. Then I covered it with blue cellophane . This allows for an oven front that you can see through and open. For the oven handle I used another button hot glued on.