The things I used for this are easy to get, the main piece is a clock motor, I used the most common clock motor there is, almost all clocks have it(A square black one saying QUARTZ) You probably already have multiple of these in your house.
In the next steps I'll explain how to build this. If you start building it, keep in mind that you need to make the rotating parts move smoothly over eachother, because these clock motors are build to rotate very light pointers, they do not have a lot of power. If the parts can't slide smoothly over eachother the mechanism will stop.
edit: user 'talty' commented below that it is uncertain if it's harmful to let polymer clay get in contact with food! So I recommend that if you use polymer clay, add a layer of harmless varnish(I don't know if that exists). You can also make the feed segments out of river clay, or completely out of wood.
edit #2: The cat feeder I made seems to stagnate sometimes, this is because the disc is too heavy for the motor. You don't want it to suddenly stop when you're gone, so make the disc as light as possible! I made a new disc out of a thin sheet of plastic, it works better. You can also look for a stronger clock motor, like this one.
edit #3: user 'spencerawr' had the idea that you could also make a small version of this, hang it upside down above the aquarium and use it as a fish feeder.
Step 1: What You Need
- clay(I used FIMO, which is a polymer clay and those are expensive if you use a lot. If you can get a cheaper clay that works fine aswell, use that) and an oven to bake the clay
- thin wood. This is for the cap on top, for the disc, and for a little block under the clock motor.
- from a clock: the motor, the second pointer, and the hour pointer
- a wide round cookie can you don't use anymore
- two nails
- cutting pliers