BattleTech Hex Base. The standard base matches the dimensions of the Catalyst bases. The pewter mech compatible base includes an oval cutout for the metal base. Onshape design files can be found at: https://cad.onshape.com/documents/2e316e4edd56fd3ba8615fee/w/a1e0c7eced5261bf459b6cc3/e/363acda9c9a49e0ffd5b4a50