Minolta makes no accessories for the exterior lens bayonet other than the lens shade.

The rings shown here are very handy for mounting all kinds of things to the front of the camera without using the filter threads. Rings remove with a quarter turn. Very close coupling is also possible since there is nothing between the accessory and the D-7 lens ring.

2" nominal Sched 40 PVC tubing has the perfect inside diameter to fit over the D-7 lens.
This tubing has an ID of 52mm and an OD of 60mm, with a wall thickness of 4.2mm.

I use PVC electrical conduit, because it is grey and is solid PVC. Cellular core PVC or ABS plumbing pipe does not work well for turning.

Stock removal is reduced, all that needs to be done is to cut a ridge that fits between the
lugs on the lens shade bayonet. A custom ground lathe profile tool cuts the ridge and required clearances in one operation.

The other end of the tubing can be turned inside to fit filters, etc. For larger outside diameters, a standard 2" coupling section can be solvent welded to the outside and turned to the required diameter. See my "Siebert Optics Eyepiece" gallery for an example of an entire optical assembly made from a single piece of tubing with the bayonet fitting on one end.