Handle it.

As you may know there are alot of old bread and butter knifes out there second had shops ect..you can pick these up very cheap.

Grind or cut off blade grind the tip of either side of handle till thin to make it easier to drill hole in either end to conect your swivel to. Some of these knifes have great handles and dont need much work these are genrally stainless so after a period of use just polish up and normally have a good weight to them. GOOD CHEAP SPINNERS.