A 3D-Printable model of the eurypterid walker from the Dinotopia books - it didn't have too big a role but the books are quite heavy on detailed descriptions and worldbuilding and these ancient mechs found udnerground without much further explanation are somewhat fascinating - this one was built resembling an eurypterid, more commonly known as a prehistoric sea scorpion (though technically hteir exact relationship with scorpions is a bit more distant) and works as an amphibious one man vehicle. The model is full scale so you can scale it to whatever size you want. There are individual parts that clip together for a movable version, a full STL of the entire machine and a SolidWorks assembly with the parts linked together so you can easily move nad pose the mech and the nexport a full stl if you have SolidWorks.
The Model was designed to be scaled down something around 1/20 but smaller or larger scales are possible too - it's full scale overall length is about 10 meters.
When printing in parts it is recommended to make the tail with more infill / wall thickness to somewhat balance out the center of mass and get it to stand on it's legs well.
I won't upload any of the original references as preview images due to copyright but if you like you can look the mup, some of them are easy to find - or get the books, they're really good.