>>8910275I honestly think the Blackarachnia mold would work well for Transmetal Tarantulas.
Nearly everything in the BA mold's robot mode fits underneath the spider pieces, with the exception of the thighs, which have biomechanical detailing on Tarantulas so they'd blend in well with the robotic spider.
The wheels would be the one new bit of engineering--attach them to the abdomen on a long ball joint, and they can move around freely, sitting flush on Tarantulas's shoulders in robot mode, or underneath the abdomen in beast mode to form the back wheels.
His sawblade would attach under the spider head (5mm port to be added there) to form the front wheels.