Very nice concept, I really love physically based games!
Good choice of engine for this one, the global illumination is gorgeous on those kinds of materials (my GPU is screaming but it's ok xD). Add a chill soundtrack, a little depth of field, some scratch details maps on your materials and it would really be a mood.
Some criticism: I would love to be able to cut the plastic while holding my clic, and the rotation to not steer in another direction that the one you give (with a lil more sensitivity too)!
Cheers fellow mecha lover o7