Nice work, Ryan! For the hidden tang knives, I find a piece of veneer or Micarta the same thickness as the tang, and then use that around the tag as the meat of the sandwich. Doesn’t have to be very exact, as I’ll be epoxying everything together, and the epoxy will fill any voids.
For a knife like the #1 Mora, I also have a piece of O-1 steel cut to roughly the same shape that I’ll heat red-hot with a MAPP torch, then use that to burn a hole for the tang if I really want to do a solid handle. The #1 tang gets narrower most of its length, so that works ok (and again, epoxy will fill any voids).
The final trick is if I’m making a stacked (leather or birch bark) handle, I’ll punch holes in each layer with a leather punch and thread the pieces on, compressing them every few. Need a bolster on the end of the tang to hold things together. I use a die to thread the very end of the tang, crank on a nut, peen the tang over, then grind it all to an aesthetic shape.
Once I get my projects migrated over, I’ll try to remember to come back and point you to them, too.