This treefrog is based on a recently discovered species called the Tiger's Treefrog (Hyloscirtus tigrinus) which has an incredible maze-like pattern on its skin. Hyloscirtus tigrinus lives in the rainforests of Ecuador and Colombia and is exceedingly rare. Scientists estimate there are only 250 adult tiger's treefrogs alive today.
You can see some pictures of them here
I've uploaded two different frogs, one for printing big and one for printing small. The frogs are designed for dual extrusion 3d-printers and are each composed of two files: a "hollow" one and a "solid" one. If your printer only has single extruder, you could print the "solid" half by itself to make a 1-color frog.
This is designed to be printed with no supports. We used Makerware's medium settings to print the frog in ABS on our Makerbot Replicator 1 (2 shells, .2mm layer height and 10% infill).
Slicing warning: this takes a while to slice! The frogs took us 13 minutes to slice with .2mm layers in Makerware.
I modeled the body in Blender from photographs of Hyloscirtus tigrinus and the pattern was generated using a simulation of reaction-diffusion.