To use, download the models here, and the tree frog model. Then combine them in your slicer app by scaling and adjusting the elevation (Z offset) of the frogs as follows:

Pawn: scale 50%, elevate +1mm
Rook: scale 53%, elevate +7.1mm
Knight: scale 70%, elevate +1mm
Bishop: scale 70%, elevate +1mm
Queen: scale 100%, elevate +1mm
King: scale 100%, elevate +1mm

You'll probably have to merge the models in order to set the Z offset of each frog without them defaulting to sitting on the platter.

It's a bit fiddly but, after a couple tries, you should be able to get everything to fit.

NOTE: Even though the models here are public domain, the frog itself is "Creative Commons - Attribution - Non-Commercial - No Derivatives". This means that, while you can do whatever you want with the models attached here, the same is not true for the frog model, or any combination of these models and the frog model (e.g. you can make a chess set for yourself, but you can't sell it or post the combined model anywhere).