I have been helping a local company integrate 3d printing into the business, they have recently asked me about polypropylene filament. I haven't found much other then the link below. Does anyone have a favorite brand, or experience working with this material? http://gizmodorks.com/polypropylene-3d-printer-filament/
A few Filastruder users have. It is rather difficult to get it to stick to anything, most people used a sacrificial PP sheet. You might try searching Soliforum and Google with Filastruder in mind.