Fixturing in a sea-of-holes bed requires the right tools. A common fixturing (clamping) solution for sea-of-holes beds are step blocks and clamps.
The High Tech Systems Nomad replacement bed uses an 10-32 (Imperial) threading, the C3D Nomad add-on bed uses an M6 (metric) threading. The C3D SO3 sea-of-holes is M6 as well.
Surprisingly, these are compatible with at least one commercial step block clamping system:
It so happens that 10-32 and M5 screws (used for the set) have the same clearance hole size - 0.201". The clearance hole size of an M6 is 0.242". The clamps in this set are slotted at a 0.250" (and a bit larger).
This which means that one can purchase one or two of these sets and use them with an M5 sea-of-holes. If one has a M6 and 10-32 sea-of-holes bed, they may ditch the M5 hardware that comes with a set and use 10-32 or M6 screws plus the appropriate washers.
I verified this by speaking to their supplier’s technical support and by putting calipers to the actual clamps (I purchased some).
Step blocks and clamps are not for everyone or for all situations - they take up room on the bed - but they are hard to beat for simplicity, easy of placement, ease of use, adjustability, and low profile nature (helps avoid collisions with the fixturing).
With a spoiler board underneath ones stock, they can provide additional “Z” over using the C3D vise - which may be useful for some projects.
As with all clamping devices (collets too!) remember to go “monkey tight, not gorilla tight”.