I’ve sold several machine heads without a case or even a base. Most of them were “beaters” that needed restoration work done, so the Buyer can decide whether to put it into a base, case, cabinet, or use it for a parts machine. I don’t care.
I have also sold some operating Singer 99 machines without a base or case that I had converted to handcrank operation. I can’t find vintage bases for them, much less a case that will close with an aftermarket hand attachment mounted on it, so I sell them without a case or a base. The end-user can buy a base or a case of their choice. I don’t make them. I have begun putting a rubber boot on the foot that is actually part of the hook assembly, and that helps keep the machine from sliding around somewhat. Hand cranking seems to make the machine move worst than using it with an electric motor, so using one on a slick surface can be a problem. I recommend setting the machine on a piece of the non-slip mats available to help keep it from sliding.
I tried one of the new plastic cases for the 3/4-siz machines for a Singer 185K that I converted to hand operation. It was a full-sized case with 3/4-size hinge pins. I won’t try another one. When the case is lifted by the carrying handle, the case flexes to let the machine fall into the bottom of the case. No damage done, but I had to pop the machine back up out of the bottom of the case every time that I took the top off of it. (Yea, I know, you’re not supposed to carry a sewing machine case by the handle, but I do.)
CD in Oklahoma