I have been using Darik's Boot'n'Nuke for several years now when needing extra effective wiping. It has several different methods to choose from, starting from a simple zero fill to a seven-times-random-1-0 twisters.
3.5" disks are made of solid metal, they don't shatter. Drillholes, sledgehammer or even just poking some holes through the adhesive stickers scratching and deforming the platters will make them unreadable for the most. Not to mention shooting a rifle bullet through it!
One good and environmental friendly way is to dismantle it: You get a nice shiny disk to use as a candle mantle or coaster, plus a pair of the best refridgerator magnets on earth! Or if you leave the platter but strip almost everything else, after attaching a piece of adhesive sanding paper (not too coarse, 400 or finer) on the disk, you get a nice 12 volt grinder to sharpen your flathead screwdrivers and wifeys scissors.