The homemade one is harder to keep clean than the EZ Milker.
Let me get the collection of homemade ones and tell you sizes.
Edited: Here they are, and now you know I'm a tinkerer. Just can't help making things, trying to improve, etc.
All of these have been hanging unused in the utility room for more than a year, so I would thoroughly clean the drench gun (and replace gaskets) and replace all the tubing and syringe bodies before using them again. TAKE YOUR DRENCH GUN to the hardware store when you buy vinyl tubing so you can get the right size. Buy more than you need.... a couple of yards.... so you can cut it to the length you want.
The largest one has a 35 cc syringe body, and that's too big for most teats.
The second largest one is actually the little plastic case that a syringe came in, and I think it's about 20 cc.
The smallest one (with the Ivomec gun) us what I used for the Mini - 12 cc.
At the feed store, buy one each of each size syringe that looks like it might be close to the size you need. At home, remove the plunger and the needle, and see how each fits on the goat's teat.
Tinker with your project. :-)
The next question is, "How to I attach the syringe body to the tubing so it doesn't fall off?"
The big one is attached with a hose clamp.
The middle one and small one are attached with J B Weld. (like epoxy glue)
Note: the background of the pic is the bamboo flooring in my office.