I recently designed and created a cardboard costume for a project in my school. I was tasked with designing a slot construction costume of a marine animal. I chose to create a costume of a starfish. The project evolved from designing the costume on paper to tracing pieces, cutting them out, and eventually assembling them. My design changed many times over the course of the project until I reached my final design, which this instructable is diagramming.

Design Brief: I was part of a group project where our group of five had to design five costumes of a common marine theme. I was tasked with designing and producing one of the costumes for my group.

Specifications:
· The costume must be wearable by a middle school sized child
· The costume must be a Halloween costume or a costume for a play or show
· The costume must be flat pack construction (flat parts and designed to be quickly and easily assembled)

Limitations:
· The costume must be made of cardboard only
· No adhesives or staples were used to attach parts
· The costume must be only slot construction
· The costume must be flat pack construction
· The cardboard must be easily obtained

Materials List

· (S1) Cardboard front arm sheet, size: 30” by 36”, Qty 2, can be obtained by half of a speaker box
· (S2) Cardboard back arm sheet, size: 30” by 24”, Qty 2, can be obtained by other half of speaker box
· (S3) Cardboard body sheet, size 65” by 43”, Qty 2, can be obtained by a large TV box, or a bed frame box
· (S4) Cardboard slot sheet, size 35” by 7”, Qty 1, can be obtained from any scraps or small pieces of cardboard
· (T1) Cutting mat, to prevent damage to the surface cutting is done on
· (T2) Utility Knife, to cut the cardboard pieces
· (T3) Ruler, to measure pieces and to trace straight lines
· (T4) Pencil, to mark cuts
· (T5) Marker, to mark folds

I encountered a problem with the cardboard I used for my costume. I came to the conclusion that a stiffer cardboard should be used for the body pieces and a much lighter cardboard should be used for the arms. The arms of my costume were very heavy and would tear the much lighter and flimsy body cardboard. Also a stiffer cardboard for the body would help it hold its shape and makes the body easier to wear and to work with.

Parts List:
· (P1) Front arm piece, Qty 2
· (P2) Back arm Piece, Qty 2
· (P3) Front body piece, Qty 1
· (P4) Back body piece, Qty 1
· (P5) Separate slot piece, Qty 10

Note:Although I chose to not paint my costume you might want to. From previous experience I have learned that cardboard bends and contorts when it is painted on one side so to combat this problem I suggest painting both sides. This will cause both sides to even out. Also painting must be done while the costume is disassembled.

Step 1: Tracing Pieces

The very first step of this instructable is cutting out all of the pieces needed for assembling the costume. For step one you are going to have to use most of the tools such as the cutting mat (T1), the utility knife (T2), a ruler (T3), a pencil (T4), and a marker (T5). This step in the instructable will be diagramming draw and cut out all of the different pieces of the costume. Some of these steps need to be repeated multiple times. The instructions below are ordered so the fist set of instructions corresponds with the first picture. The pictures below have dimensions along with slot and tab positions on them.

Front Arm Piece (First Picture)
Use cardboard front arm sheet (S1) to trace the dimensions of the front arm piece (P1). Draw the dimensions (documented on the corresponding picture below) onto the cardboard front arm sheet (S1) with a pencil (T4). Be sure to use a ruler (T3) to make sure all lines are straight. Use a marker (T5) to draw the lines for folds. Note: the flaps of the front arm piece (S1) have slots on them and will be folded. Place the cardboard front arm sheet (S1) with dimensions outlined onto a cutting mat (T1). Using a utility knife (T2) cut on the lines drawn by a pencil (T4) and not the marker (T5). Next fold along the lines outlined by a marker (T5). Cut out the slot holes D, E, F, G, X, and Z using a utility knife (T2).

Back Arm Piece (Second Picture)
Use cardboard back arm sheet (S2) to trace the dimensions of the back arm piece (P2). Draw the dimensions (documented on the corresponding picture below) onto the cardboard back arm sheet (S2) with a pencil (T4). Be sure to use a ruler (T3) to make sure all lines are straight. There will be no folds on this piece so the marker (T5) is not used. Place the cardboard back arm sheet (S2) with dimensions outlined onto a cutting mat (T1). Using a utility knife (T2) cut on the lines drawn by a pencil (T4). Using the utility knife (T2) cut out slot Y. Note: be very careful cutting the tabs out because they are critical to assembling the costume. There is a mistake in the picture below there is a tab drawn in the place of slot Y. I made a change to the design and there is no tab in that spot.

Front Body Piece (Third Picture)
Use cardboard body sheet (S3) to trace the dimensions of the front body piece (P3). Draw the dimensions (documented on the corresponding picture below) onto the cardboard body sheet (S3) with a pencil (T4). Be sure to use a ruler (T3) to make sure all lines are straight. Use a marker (T5) to draw the lines for folds. Note: the flaps of the body piece (S3) have slots or tabs on them and will be folded. Place the cardboard body sheet (S3) with dimensions outlined onto a cutting mat (T1). Using a utility knife (T2) cut on the lines drawn by a pencil (T4) and not the marker (T5). Cut out with the utility knife (T2) the face hole. Cut out with the utility knife (T2) tabs B, C, H, J, I, and K. Note: be very careful cutting the tabs out because they are critical to assembling the costume. Cut out with the utility knife (T2) slots A, both X, and both Z. Note: be very careful cutting the tabs out because they are critical to assembling the costume.

Back Body Piece (Fourth Picture)
Use cardboard body sheet (S3) to trace the dimensions of the back body piece (P4). Draw the dimensions (documented on the corresponding picture below) onto the cardboard body sheet (S3) with a pencil (T4). Be sure to use a ruler (T3) to make sure all lines are straight. Use a marker (T5) to draw the lines for folds. Note: the flaps of the body piece (S3) have slots or tabs on them and will be folded. Place the cardboard body sheet (S3) with dimensions outlined onto a cutting mat (T1). Using a utility knife (T2) cut on the lines drawn by a pencil (T4) and not the marker (T5). Cut out with the utility knife (T2) tab A and both Y tabs. Note: be very careful cutting the tabs out because they are critical to assembling the costume. Cut out with the utility knife (T2) slots B, C, H, J, K, and I.

Individual Slot Pieces (Fifth Picture)
Use cardboard slot sheet (S4) to trace the dimensions of the separate slot piece (P5). Draw the dimensions (documented on the corresponding picture below) onto the cardboard slot sheet (S4) with a pencil (T4). Be sure to use a ruler (T3) to make sure all lines are straight. . Place the cardboard slot sheet (S4) with dimensions outlined onto a cutting mat (T1). Using a utility knife (T2) cut on the lines drawn by a pencil (T4). Note: be very careful cutting the tabs out because they are critical to assembling the costume.

Step 2: Assembling the Body

Assembly starts by putting the body together. This step is a fairly simple step in the process. All it is comprised of is slotting tabs into slots. Anytime during this step you may think you need more slots to keep the costume fitting together well. To do this you need to make two slots in the same area and make another separate slot piece (P5). Then you slot the separate slot piece into the slots.

Body piece assembly
Start by placing front body piece (P3) on top of back body piece (P4). Insert tab B into slot B and tab C into slot C. Insert tab A into slot A. Then Insert tab H into slot H and tab J into slot J. Insert tab I into slot I and tab K into slot K.

Step 3:

This step is also a fairly simple step in the process. Again all it is comprised of is slotting tabs into slots. For this step in assembly you will have to do it twice. Once for the right side and once for the left side.

Arm Piece assembly
Fold all of the flaps back. Insert tab D into slot D. Then insert tab F into slot F and tab G into slot G. Remember to do this step twice.

Step 4:

The last step in the costume assembly is to connect the arms with the body. This is done through slotting the last pieces together. Most of the separate slots (P5) will be used in this step. Same as the previous step, this step has to be repeated for the right side and the left side. This step will complete assembly and is the conclusion of my instructable.

Final Costume Assembly
Lay the completed arm piece next to the completed body piece. Insert tab Y into slot Y. then insert tab X into slot X and tab Z into slot Z. The final step in this process is to insert tab E into slot E. You have to repeat this step for both the right and left side.

The only step left is to put your completed costume on and enjoy it. The costume for me came out very well, and I hope it has for you.