I've been making calls for over 16 years now and selling them for 10...Started out making box calls, switched topot style calls for 8 yearsand have recentlygone back to making box calls...Long boxes and Scratch boxes to be exact.
There are two ways to make pot style calls, either with a lathe or with a drill press...Neither way is easy, there are tolerances that have to be maintained, wall thickness', bottom thickness', distances between sound boards and striking surfaces...Using the proper glues...These all affect the sound of the call.
Here's a link to a site dedicated to making and collecting calls where you can ask questions about making calls:
http://www.customcalls.com/cgi-bin/yabb2/YaBB.pl