I use the same tip. I use a drill with a support and i printed out a drilling guide. It's not perfect but with adjustements it's ok.
Oh, yes, for a clean drilling, use this tool:
// TECHNO jam #1 with LXR and Octatrack //
ALL sounds come to LXR!!!! No sampling, all realtime, custom patch, just
some FX and Filters (dark reverb, echo, filter) with octatrack.
Yes, I bought and cut aluminium in a little factory near my home. Nearly 20€ (cut and bought alu)...it's not expensive and the work is clean! But all drilling by me.