I have put together a set of 3D printed bases to use my large collection of pre-painted plastic minis with 1.5" hex-based TFT.
The 3-hex and 4-hex adapters have a little wiggle room, so some putty or 2-sided tape will hold the 2" based minis in place. The 1-hex adapter seems to fit 1" based minis pretty tightly.
The standard 7-hex base is just flat - I'll have to glue dragon minis on the base, or use the alternate 7-hex base with "Huge" sized minis.
They can also be used with cardboard "pawn" bases (although I have another set with integral pawn bases that I'll probably upload).
I know I could have done the same with plasticard, but I think this looks better (well, better than what I can do with plasticard).
The bases are on Thingiverse You may need an account to download.