MegaMekLab
MegaMekLab is a freeware BattleMech and combat vehicle creation program. Saved files are compatible with the computer game MegaMek. [1]
Like its associated program, MegaMek, MegaMekLab is Java-based, and runs on any system that supports the OpenJDK Java platform.
MegaMekLab can also be used to print PDF record sheets for created ’Mechs and combat vehicles, as well as battle armor, ProtoMechs, Dropships, support vehicles, aerospace fighters, and WiGEs, for use in tabletop games of BattleTech.[2][3]