I build open-source Eurorack modules, I can sell you some.
Nearness, In CV, Clock divider, MIDI 4+1 and AC+MULT are among joeSeggiolas most popular products.
Minimal panning mixer
Terry Riley's "In C" implementation for Eurorack
3x4-way multiple and 2xAC coupling module
Programmable Eurorack clock divider in 4 HP
MIDI to 4x CV/gate, with polyphonic and monophonic voice allocation modes