These were modeled for my partner's Battletech mechs, as such the hex side is just smaller than the standard hex side length. The bases are 30.5mm edge to edge.
The bases have a slight raised edge so you can place terrain around the feet of the mech. Only the flying object base has space for the washer as the models themselves are sometimes weighted.
Let me know if you'd like a standard base with space for a washer (if your washers are larger than the standard base).
He also wanted hex bases for flying vehicles, so there's a hex with a hole in it and a post that fits in case you want to place your flying stuff on the map.
Finally, he asked me to make him a smaller hex base for hovercraft, I think two of those small hex bases are supposed to be able to fit into one map hex, but don't quote me on that.
The author marked this model as their own original creation.