I built this really simple jig to make a modular gaming table / board for the games I play.

The problem I found with modular terrain is, that the individual plates often move around when someohne pumps into the table or larger terrain pieces.

So I made I jig to add magnets to my game board so the plates stay together. For these Magnets I use 8x5mm round magnets. The magnetic force is sufficient and they are quite cheap.

The jig is designed to drill holes into your modular tiles and keep track of which magnet needs to be inserted in which polarity.

What do you need for assembly?

2x D=3mm, L<3mm magnets

2x M3 Screws (8mm < L 14mm)

The assembly process is quite simple:
Insert the D=3mm Magnets into the Lever part - make sure the magnets have opposite polarity as shown in the picutre. Then attach the Lewers to the main body using M3 screws.