Would a naked sewing machine still mostly work?
 

I do some training with handcranks. I have noticed some pics on here of naked sewing machines. I remember a Cinderella and some aluminum framed one. It got me thinking about using one in teaching. I am assuming I'd have to mount spool pins and bobbin winders somewhere, but does anyone know what machine would be a good candidate for this? Has anyone done it? Complications? Yea, I know my mind is twisted, but I am still in love with the 1939 Plexiglass bodied Pontiac

Cinderella works but it isn't usual - plus you can't see an actual stitch formation real easily. I prefer to demo a long bobbin to see a stitch formation. I have removed the plates & put plastic over the whole base to watch a long bobbin. I made holes for the needle and feed dogs. I recommend a White Long bobbin for that. Much easier to see. The white's nose plate doesn't come off nice like the Singers. A Singer 99 could have a plastic nose plate and a plastic over the throat area. It is a bit hard to see when fabric goes through. Same with the 15s. Some long bobbin shuttles are on the right and easier to observe with the plastic while sewing on fabric. The principle is the same. The thread always goes through a tension. A lever pulls the thread through. The needles all have groves for the thread. The needle makes a loop. Bobbin thread passes through. Somewhere on here is a video about the human sewing machine. It is very helpful.

My first thought was show them the human sewing machine video, https://www.youtube.com/watch?v=tiSnXpPGRiQ