CS mount custom shell: 2BitToy Camera+
This mod replaces the whole shell of the original GB camera. It can be used with CS lenses and has a slot for an optional infrared cut filter (an unmodified GB Camera without an IR-cut filter also sees infrared light). The 3D files can be bought or a print can be ordered directly on Shapeways. See https://2bittoy.carrd.co/.
CS/C Mount by Herr_Zatacke
Can be used with low cost CCTV lenses (most are CS mount) as well as C mount cine lenses. 3D model listing on Thingiverse.
D Mount by W33dWiz420
Can be used with D mount cine lenses. 3D model listing on Thingiverse