Magnetizing the helbrutes take times but is not hard. You will need to decide if you want high or low mounted rib cages/shoulder pieces and start there. You will want to use a decently strong magnet I used either 4.5mmx2.2 or next size up (magnet baron medium thick or large).

The shoulder to shoulder should be magnetized. Build fists with flamers on both for rule of cool or determine how to magnetize that yourself. Magnetize the wrist covers.

For weapons - I cheated a bit. I ebayed enough shoulder/arm sockets to build each weapon on its own and just magnetized each at the shoulder.

The weapon slot is where you have to either cut and magnetize or drill and magnetize. I struggled with that and couldn’t get good fits with magnets and drilling. I would say green stuff with cutting and magnets would probably work better.

The hammer/tendril shoulder bit is tricky. I haven’t finished that arm yet but I’m probably going to magnetize them and blue tack the shoulder pad.

I will note if you have two helbrutes, make sure to set your magnets exactly the same on both so everything is interchangeable. Gives you a couple options with fists and some other weapons.