I think Serum's 2nd option is best. However, a 16mm drill bit will cost you a pretty penny. The cheapest Mcmaster-Carr sells them for is $23, and that's for a reduced shank drill bit that requires a drill or drill press with a 1/2" chuck.
SH Z-Car, Custom Crawler, 8s Savage, 12s XTM XLB 1/7 buggy, 4wd 4-link rear/IFS Pro4 truck, Custom Hyper 10 Short Course, Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz
I now have a 6mm Aluminium 'Torpedo' replica for the E Maxx (you could beat a whale to death with it) = cost me 4 ounces and a couple of pints :dft012: