Upgrading finished 28mm figures with magnets

[Gonzo100100]

I would like to upgrade my 28mm figures with magnets.
I have few ideas and few questions.
My metal figures are on 25mm x 2mm round MDF bases.
Most of my plastic figures are on 20mm x20mm x 3mm square MDF bases.
Then I have 3D printed movement trays both, for rounded and square bases, 1mm thick bottom and on top of it 2mm thick rounded slots and 1mm bottom on top of which are 3mm square slots.

I like the bases for my figures thin and if possible, I would like to avoid adding thickness to them.

My idea is to install magnets in the bases of my figures by engraving a proper slot in the bases. Also, to install magnets in the slots in the movement trays by engraving a right size hole. I think that my engraving tool should work well on the MDF bases but I am not sure it will work well enough on plastic movement trays.
My questions would be what magnets would work best? What size? Would 0.5mm thick be OK, especially for metal figures? If 0.5mm thick is ok, then what diameter?
Does anyone have experience with adding magnets to finished figures?

[tomrommel1]

I would say the slimmer the magnet the bigger should the diameter be. I use 2mm thick magnets which have a diameter of 5mm. I use washers as bases so they already have a hole were you can pop the magnet in. If you want to make a slot in plastic bases turn down the speed of the engraving tool. The shaved of plastic might block the bure bit of the tool otherwise because of the heat.
Hope that helps

[Kelly_]

In place of two magnets, you could use a magnet to steel connection... I am planning on putting small diameter screws into the base of turrets with a single magnet in the bottom of each ship barbette to allow them to swivel freely or be changed out.  I have had trouble with magnet-to-magnet attraction pulling small size models apart, and with the turrets being less than a quarter inch across, the strength of the connection should not really be an issue on those.

If your models are fairly balanced on their bases now and you don't need the connection to be load-bearing, you could either put a small pilot hole through the models' legs for a steel nail or screw to meet up with a magnet in your tray, or cut thin sheets of steel to epoxy into the recesses of the tray to meet up with magnets in the bases of the models.

[fred]

Magnet to steel options are worth considering. Makes things generally simpler, as polarity isn’t a problem.

You can get steel paper, which is pretty thin, and is a good option for lining movement trays.

Small neo-molybdenum  are very strong, you probably will only need ones a few mm across to get enough strength to hold a figure to a movement tray. It depends a bit on whether you are wanting to keep the figures in place for transport, or just during gaming. Probably worth getting a few different sizes to test which fit within your bases, and which provide enough ‘stickiness’