Bob,
Polypropylene has similar properties (not identical) to Delrin when it comes to flexibility. Delrin, a trade name of an acetal resin (Celcon is another trade name), can literately be tied in a know without breaking but it's VERY difficult to paint. Acrylics works well on Delrin and other "engineering plastics" which PE and PP are members of. I run PP because it processes MUCH easier than Delrin and the parts are pigmented a dark brown so if your paint chips off, and it will over time due to handling, you won't be staring at a white piece. I do plan to keep these detail parts in stock on a regular basis. Molded parts need to be run in batches but the urethane castings can be made as-needed. I sold out of the #1 stirrup in about 15 minutes and #2 is now gone but I'm going to run more after next week when I receive a piece of new steel for my injection mold. Jim King Smoky Mountain Model Works, Inc. Ph. (828) 777-5619 <www.smokymountainmodelworks.com>
