I purchased a used one as the piece is a bit pricey, but the machine ru-vid.comUgkxG6fbm3cHBd7CNTjk5D-dwYe9c9tCB9ZN has surpassed my expectations. We sand small parts by hand often, sized around 1"x1/2," and specifically look for a piece that's designed to be vertical. The motor has plenty of torque and great speed settings. The only inconvenience I had is that the disk measures 5" where we trim 6" stick-and-sand disks down easily by mounting it then cutting with a box cutter.
In a small shop like that, it’s not practical because you always moving it. He should attach it to a plate the size of a mat, so that he is standing on the plate when using the grinder. Then attach wheels to the plate that only engage when he tilts it to move it around the shop.