I have not read through all of Coldin's Trapmaking Guide yet, have checked on this forum as well, but have not found this as of yet, apologies if it's already been brought up and dismissed.
I would like to see a Trap the Soul trap implemented for synergy and improvement with the current trapmaking system (which I would love to see developed further) - especially as trapmaking might be neglected (further, some might say) with the introduction of soul gems to Cannith Crafting recipes.
Some might also like to explore other options for gaining soul gems without requiring being a Wizard or having greensteel/epic items. While I am interested in such discussion, it has potential for derailing the thread into a silly class vs class vs crafting argument. I suspect that we might learn more from opinions on improving the trapmaking system than such a thread...
I don't actually have a mechanic at the moment, I do not know what a reasonable amount of trap-parts and special components this should take. I guess what seems off-putting is that UMD is often a more elegant option available than employing traps - perhaps if there were higher level magical traps available...