I used this to fabricate a series of urns based off Google searches entitled recollections. Here's a video of the process in case you wanted to see:
Step 1: Getting Started
For this instructable you should be comfortable with throwing on the potter's wheel and should have access to one. You should also have access to a band saw, wood shop, laser cutter or something that will help you make your plexi template.
You should also be familiar with pottery terms like throwing and centering and pottery tools like ribs and needle tools.
For this you will need:
-potters tools: rib, sponge, needle tool
-plexiglass at least 1/8" thick, 1/4" preferably
-bucket of water
Step 2: Making the Template (Profile in Plexi)
What you will do in this step is cut out the profile of HALF of the shape. You only want to cut half because the wheel will make the shape all the way around. Sort of like when you're in elementary school and you fold a piece of paper in half then cut a arc. When you unfold the paper, you get a heart but the cut you made was only half of the heart.
For this shape, I used Adobe Illustrator to create a file that I sent to be laser cut. I've attached the file but make sure that your strokes and colors match whatever the settings are for laser cutter you end up using.
Alternately though, you can simply sketch or draw onto a sheet of acrylic plexiglass and cut that using some sort of saw. I like to use this method when I'm cutting a profile in plexi for using on the plaster wheel. I will first sketch the shape, then cut it out using a band saw. I can go in with different grit sandpapers to then smooth out the shape.
Step 3: Centering
Once you have your profile made, you can hop onto your potters wheel. In the next few steps, I will briefly go through the steps to making a cylinder. If you already know how to make a cylinder, go ahead and skip to step 5. This is not a particularly detailed portion of this instructable because I am assuming that you are comfortable enough with making forms on the potters wheel. For more detailed instructions, see:
If you don't know how to make a cylinder, I'll start with centering. In this step, you want to cone your clay up with your two hands, then press down on the cone with your right, then cone up the clay again. You're going to repeat this pattern of cone up, press down until your clay is centered. Remember to clean off any slurry with a rib or sponge.
Step 4: Compressing
Press down with your first and middle finger into the center of the clay. Continue going down until you feel like the distance between your finger and the bottom is about .5 inches. Then take a needle tool and poke down to double check. Continue to press further if need be. Leave as much clay on the bottom as you think you'll need to trim a foot.
Then pull out from that center point towards 6 o'clock. Use your fingers to compress the clay along the bottom to make sure that there are no air bubbles and the particles are aligned. Don't forget to clean off the slurry here as well with either a rib or a sponge.
Step 5: Pulling a Wall
Once you're done compressing, press in slightly with your right hand. This will begin to build your wall. Then dig a slight trench along the bottom of your cylinder with your finger. Use this to begin to press into the clay with your right hand. Match the same amount of pressure with your left hand, which is inside the form. Although your left hand (the one inside the form) will be slightly below your right hand, they should be moving in tandem using the same amount of pressure. You can lighten your pressure as you get to the top if you notice the wall is thinner on the top.
Continue this cycle to pull your wall up.
Step 6: Using the Plexi
Once you have achieved a cylinder that is more or less even walled, place the piece of plexi next to the form to make sure that it is the height you need. If it isn't you can always collar it in using both of your hands to apply even pressure around it, moving up slowly from the bottom.
Once your cylinder is the desired height, begin to press slightly into the clay. You will need to make sure that there is nothing obstructing the plexi on the wheelhead. This is to make sure you can rest the plexi slightly on the wheelhead to ensure the form is properly at a right angle. Make sure there is plenty of water on the wheelhead so that the plexi can glide along.
Press slightly in with the plexi while pressing on the inside of the form. Clay will begin to scrape off. Ease off of the wheel and remove the plexi slowly. The more you ease, the less chancees there are of denting the wet clay with the hard plexi. Scrape off the clay that has built up on the plexi.
Continue to do this until you have achieved the form. Make sure you are always supporting the pressure on the outside with pressure on the inside. Also make sure that you are not throwing your form off center.
Step 7: Finishing Up
Make sure you pay attention to the rim before you are done. Compress and clean off the extra slurry.
You can see here what the form looks like once it's done. You can do it too!!!!!!