Their used to be shops in every city that fixed cracked dashes, armrests , etc. by plastic welding. Apparently no one could compete in price with the dash caps. If you want to try it, there are still lots of places that will sell you the equipment. arizonatools.com is a good place to start, click on welding torches then plastic welders or Google "plastic welders". If you can find a copy of "Motor Auto Body Repair" manual at your local library it has a detailed section on the process and you can see what you are getting into. I have seen plastic welders at Harbor Freight Tools for 30 bucks, don't know about the quality, but for one time use...