How to make magnetic movement trays for warhammer etc.
Get your supplies together. I picked up enough 0.9mm steel plate from an eBay seller to kit out a 3000pt army for about £8, and magnets for about £3. I already had everything else I needed.
This method works out about £1-2 per unit. I start by cutting some lengths of sprue to use as a border for my tray. File off any lumps and bumps. They don't have to be perfect.
Mark out the footprint of your unit plus the surrounding sprue. Leave an extra millimetre so its not too tight. Cut it out using tin snips, a hacksaw or suitable power tool. File off any sharp edges.
Scratch up the top surface of your steel - this will let the superglue and white glue get a decent grip. I just used a file in a circular motion.
Glue on your sprue borders. Take the opportunity to make sure everything fits at this stage, or you are going to be swearing later. File any excess sprue off at the corners.
Glue magnets into the bases of your unit. I used N40 strength 6mmx2mm. These are pretty strong, but there is a layer of sand to go between the steel and magnet, so this will reduce the strength.
Use modeling putty to 'dress' the sprues. Make sure you don't get any on the inside or bottom edges, or your models won't fit. You can go for a smooth look, but I've gone for 'muddy terrain'.
Pack modeling putty around the magnets in your models. This will help stop the magnet detaching from your model when removing it from the tray.
Paint the interior of the tray with white glue, and sprinkle fine sand onto it, taking care not to get on the sprue edge. Shake off excess. Once dry, give the whole piece a coat of glue to seal it.
Once everything has dried, base coat in a colour to match your model bases.
Wash and drybrush to taste, and add some flock for effect.
Test fit your unit, if you have done it right, all should fit snugly.
Hey presto. You can hold them upside down no problem, yet they are easy to remove once your soldiers get killed!