If you want to start inexpensively, build your own 3D printer. Here is a recent article.
http://www.computerworld.com/slideshow/detail/128090
“5 cool 3D printers for less than $500”
Though not mentioned in this article, I really like the Rostock/Delta design. Steve Graber’s “Cerebus” looks great and affordable. You can build it to print with ABS, PLA, Nylon, Carbon Fiber filled filament, Wood filled filament, etc.
https://www.youtube.com/watch?v=lmuobEa7Tt8&list=UUn8_8lCxnFYEPLXFlKSxRCQ
https://github.com/grabercars/Cerberus
Steve uses the magnetic ball joints developed by Werner Berry. Very innovative!
https://www.youtube.com/watch?v=x6PLHl0HHq8
Thank you both for the tips. I’d rather buy an assembled 3D printer, as my time is spread thin. Once I do, I have some ideas for making some greenhouse parts, that would also work for a trellis. When I did have a greenhouse, I had overhead string supporting my tomato vines. Now, I envision making some plastic bars with multiple holes and a hanging loop on either end. The loops would hang on horizontal supports (probably PVC). Wooden rods would go through the plastic bar holes reaching across the greenhouse. Plastic clips would hang on the wooden rods and support the strings. I’ll make all the plastic parts with a 3D printer. Greenhouse will be built with combination of round wooden posts, and PVC tubing. Ellendra, I would like to hear of your trellis designs and how it works out, thanks!