Where does one find powdered resin?

In my post on Making Bird Calls I forgot to mention the grief we went through trying to locate "powdered resin" Today someone found my blog by searching google for "bird caller resin to purchase" so others must be having the same grief.

MATERIALS: 2" hardwood, eye screw, resin powder

Take a close grained hardwood such a rock maple or mountain ash, about 2" long.
Drill a hole in one end, slightly smaller than the screw threads of your eye screw. Turn the eye screw into it. Unscrew the eye, put a little resin powder in the hole. As you twist the screw back and forth in the hole, very slowly, you can make a chirp chirp or trill in loud, clear notes.
With practice, this device will produce an astounding variety of bird noises.
Paint or decorate if desired.
Elective 12h in the Bear Handbook

To those searching, the powdered resin that worked for us was simply the resin bag that a baseball player or bowler would use. Buy it at Amazon. Perhaps climber's chaulk would work also. We did not tear the bag open rather we placed it on the eye screw and shock the sack a little. When the screw was white with powder the scout put it into the block of wood for a 2nd time and chased birds.

The calls do work and work well. I want to make one for myself now.