dipswitch multicart

[Frotz]

I'm thinking about making myself a dipswitch-style multicart. I found a 512-in-one design here: http://www.xs4all.nl/~rdemming/Atari/MultiCart2600/index.htm which does only 2K or 4K roms. Does anyone here know how to make a simple dipswitch multicart that handles bankswitching?