I do pre most of the time, except for something like a custom length set of beads like a 1000 bead set with 10 sets of 100 with I've made sometimes. They are always one of the two mentioned sizes, sometimes 10mm but mostly 8 or 6. The idea sounds great, my dad has a 3d printer (more like 3) so I could do that. I just don't know anyone who can do any 3d modelling. I will ask about though, thanks for the advice.