If your fingers aren't as strong as you would like, you may consider making one of these or getting it from me. It is simply a 16p nail bent at a right angle, and hammered flat to act like a screw driver. Made from the finest American exported scrap car metal, shipped overseas, made into nails, and shipped back to us.
wipLstix are very handy travel violins invented and made by me in my shop in the southern Appalachians. The length between its bridge and nut is that of a standard violin, but the body has been minimized to maximize portability. wipLstix is a self contained unit, complete with its 1/8th size bow and inflatable chinrest, all fitting inside a 2" diameter by 24" long watertight traveling tube! The case will also nicely accommodate the chunk of round rosin of your choice.