1/4 inch spring loaded "router bit" ink pen

I needed a way to run my Maslow to check out some accuracy mods I'm doing without wasting plywood. I saw there were pen holders to replace the router, however I wanted to keep weight of the sled equal to when I was cutting so here is a small 1/4 inch "router bit" pen that can be switched with a router bit and draw on paper. I hope I don't need to say this but don't have the router turned on when you use this. This pen is spring loaded and uses a standard ink roller pen cartage.