Almost exactly a year ago I finished up my mini Tau force, you can see them all together here: Operation House Party. I haven't done anything with them but about a week ago there was a chat amongst our local Nerd Herd (TM) about how to magnetise the weapons on Battlesuits and since I've been magnetising pretty much everything for as long as I've been hobbying we thought it would make a useful post here. This post assumes you have a drill/pin vice suitable for the task, and are familiar with its use.
Before I get onto the specifics of Battlesuits, I thought I'd point out the most important aspect in magnetising: polarity. Get this right and ultimately anything you magnetise will be compatible with any other item you've magnetised. This has lead to me being extremely silly and onetime had a Terminator running around with the arms from an old box Dreadnought - definitely not narrative and sadly not recorded in an image.
Anyway, after this ridiculously long pre-amble, on to the meat and potatoes of the post and how I magnetised my Battlesuits.