If going thru thin balsa, you could use a fine sewing pin. I have three sewing pins I use for building. I have the thick t-pins for stronger hold, a medium diameter white-bal-headed pin for les strength holding duties, and yellow-ball-headed pins for delicate holding operations. If I was having a problem drilling thru to each point, I would take the yellow-head pins, then push them tru until all holes were filled correctly, then one at a time remove the pins and drill the hole with the pin-vise using the push pin hole as a guide to help the bit go the right direction.