How about a treadle mechanism from an old sewing machine?
That would be nice for an old scroll saw of mine that is sitting on a shelf.

From pictures of antiques I see some had seats attached.
My original plan was to have a seat As part of the design. That may still happen.

Another thought that is rattling around in my head is to have an articulated treadle so one end could be used while standing for a quick touch up and the other end could be used seated.

jtk