Introduction: Multifunctional Paper Weight and Pencil Holder
This instructable will explain how to make a multifunctional paper weight and pencil holder out of plaster.
- Sanding board
- Plaster powder (2 cups)
- Tap water, room temperature (3 cups)
- Cutter and/or scissor
- Large polypropylene sheet (60x60 cm)
- Scotch tape/cello-tape
- Stirring tool (preferably spatula)
- Optional: liquid colour
Step 1: Drawing the Net
Use this video if needed to learn how to draw a pentagon in order to be able to draw the net displayed above. Use a pencil to draw the net on polypropylene paper. The eraser will come in handy here if any mistakes are made. Using a ruler, make each length of the pentagon 3.5cm long. To speed up the process draw one pentagon, cut it out, and then use this cutout to trace the remaining pentagons as they should all be of equal size anyway. If preferred, feel free to draw the triangles separately to be able to draw flaps on the side-edges of the pentagons to simply stick the pieces together in step #3.
Step 2: Cutting Out the Net
Use a cutter (recommended) or a pair of scissors to cut out the net. Cut out the different pieces and separate them, use the image on the left above as a guide to know which parts need to be cut out.
Step 3: Taping Polypropylene Parts Together
Use the tape to stick the different shapes together to create the half-decahedron shape. Start by taping the pentagons into the shape represented in the largest image above. Continue to stick the triangles on to resemble the image shown on the top right. Do NOT stick tape on the inside of the mold, strictly stick it only on the outside. If stuck on the inside the hardened plaster won't come out as it will be attached to the tape. Stick on another layer (or more layers if necessary) of tape to give extra support. Make sure to secure any flimsy edges, corners and especially holes with extra tape. Do not leave any gaps (except for the opening on the top) so that the plaster won't leak through when it's being poured into this polypropylene cast.
Step 4: Making Plaster and Pouring It Into Mold
Firstly, wear an apron to protect clothing and optionally goggles to protect the eyes. In a bucket, combine 2 cups of plaster powder and 3 cups of water. Add in the water first, and then the powder. Stir the mixture slowly with a spatula or any viable stirring tool available to combine the ingredients together. (Optional: add 30 drops of a colour of choice and mix it in.) If stirred too vigorously the plaster might splash everywhere and possibly get in your eyes, be careful. The plaster hardens in 10-20 minutes time, so don't take too long to pour it in. After it has been mixed, it's time to pour it into the polypropylene mold. Fill the plaster right up to the brim of the mold. Let it rest for at-least 40 minutes.
Step 5: Removing Mold
Gently tear off the polypropylene mold, the goal is not to break the hardened plaster. It's helpful to start off by peeling off the tape, and then working your way through the polypropylene pieces. This cast isn't needed anymore, so it can be thrown into the bin or be recycled.
Step 6: Sanding
Using the sanding board, firmly hold the shape and sand the base of it. Sand the base in an up-and-down movement or in other words sand the base up and down the board.
Step 7: Drilling Holes
Choose 3 faces of the shape (3 of the 5 pentagons on the sides) to drill one hole each into. Pick 3 faces that are right next to each other, in a consecutive order. Using a drill, drill one hole into the center of each pentagon. Don't go all the way through the shape, stop halfway through. Eye-ball the halfway mark by stopping at the center of the top pentagon. Use the images above to help visualize this process. Remove excess plaster bits from the drill before starting the next hole. These holes will be where the pencils will be placed.