really struggling casting a "coin"

[map1984]

Hi,
my friend wants some tokens making for a board game, I told him this would be simple to do but it's turned out to be anything but- I've tried several ways of making this token (looks like a coin, with details on both sides), firstly I assumed i'd just make a 2 piece silicon mould, this seemed ok, but the coin always seems to deform, the mould has keys in it so it aligns ok but it looks like a coin that's had a car run over it!
As a solution to this I thought well I know I can cast one side no problem (we tested it earlier) so I cast both sides separately each in their own one piece mould with the intent to glue them together...but...I realised the back of each doesn't necessarily stay flat as it cures and I don't fancy sanding them all down just to glue them up!

ANy thoughts or advice would be brilliant, the token is 35mm diameter and 3.5mm thick.
Thanks in advance,
Mark.

[mangozac]

There's no reason why this shouldn't be trivial. What resin are you using?

[Fleafa]

Could you post photos of the mould set up and the coin? If the mould is too thin, pressure used to hold the two halves together could be squeezing the cast thinner.

[rattrap]

I cast coins for my sons fantasy miniatures company which are the same size and thickness as a 2pence coin. To add weight to them I use a thin washer in a split mould together with filler powder and Cast Magic powder from Smooth On to add a gold finish. It works very well, and would solve your issue.

[map1984]

Excuse the slow reply, been a bit busy. I'm still struggling. The two piece mould just seems too difficult for such a small item both in terms of precision and volume, rattrap I'd love to see your split mould or hear any details you've got about it. Cheers, Mark