Define homemade
If you have a lathe and access to the right materials then of course you can make the basics oh and a milling machine aswell to make a grip then your set.
All the commercially made ones are made in the same way, just in larger amounts.
If you want to go the electro route then that is actually easier (electronics engineers of course) plenty of info to be found on tinkers forums etc.
Conversions of existing designs is a more practical idea.