Plastic and resin models are soft enough that you don't actually need a drill. I magnetized all my Tau weapons by hand and with 1/16 x 1/32 magnets. Just some pointers when you do this, because resin is so soft.
1) Have a good clean drill bit
2) Take a piece of junk plastic and do some test holes
3) Mark the center spot where u want to drill, IE jam a pin into the spot to form a pilot hole. This way your drill bit won't wobble all over when u start.
4) Go slow an use minimal force. Let the drill bit do the work. Too much pressure and the bit could punch through or you might deform the resin.