I have had the idea to essentially reverse engineer one of my tube calls and design it in SolidWorks and 3D print it for quite some time. I finally sat down and spent some time on it and after four revisions have a call that very closely mimics my turned tube calls. The sound is surprisingly really good and they run pretty easy as well. They will certainly not take the place of a good handcrafted call but they offer an inexpensive alternative for someone that wants to try a tube without dropping good money on a custom call.
I bet they would play just fine.