3 U modules I have purchased in addition to the SV-1b are Maths and polivoks.
As an alternate sound source/oscillator I 6 hp version of braids seems like a highly recommended balance to the SV_1.
I wouldn't bother with a second voice in a case this size, personally
Veils and Batumi round it out.
good choices - download the 'maths illustrated manual' - it's a great learning tool and jumping off point for patch programming - one of the most powerful techniques in modular synthesis - work your way through it a few times and try and work out how and why the patches work!
Very likely will add O-CTRL as CV sequencer.
Clocksource can either be SV-1b, O-CTRL or DAW via MIDI.
or maths
Don’t have a clock divider per se. do I need one ( not likely to need precision from this rack ) ?
-- YoungNorway
maths again - just remember though maths, like most 'swiss army knife module' can often only be used for one thing at a time...
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities