ABS is very similar to polystyrene since ABS is mostly that polymer (about 50 to 60%), its fairly strong and not that brittle. Another, more common filament, for 3D printing PLA (also the cheapest at $10/kg) is much more brittle and more sensitive to warping at higher temperatures, and difficult to sand.

ABS sands easily and can be bonded with most plastic cements. I typically treat my ABS 3D prints with acetone which relieves stress in the plastic and strengthens it. Almost all the ABS items I have 3D printed passed a 4ft drop test to a cement floor, the same cannot be said of 3D prints made with PLA filament.

While I am fairly good at printing with ABS, there are other polymers available, that are even stronger, at even higher price points. Kevin Cespedes at Aerobotix ; https://www.shapeways.com/shops/cespedesign-multimedia , uses a white nylon polymer and charges accordingly.

There are many other polymers available such as simulated wood, glow in the dark, and PET which I have yet to try. There are also highly flexible polymers available; even custom 3D printed running shoes can be made, just search the internet.

I purchased two Ender 2 printer kits for $175 about 1 year ago and they both have more then paid for themselves with all the high quality parts that I made.

Bruce,

Which 3D printer do you have ?

Dave F.

I have two Creality Ender 2's which still cost $175 at: https://www.3dprintersonlinestore.c...ender2-mini-kit

These are kits, so some assembly is required. Chris Taylor (of Naramlive.com) has an excellent YouTube channel on 3D printing, T3DP, and has some very detailed videos on how to put these kits together and adjust the printers to get high quality results https://www.youtube.com/watch?v=SAMPanw2am8.

I routinely get 0.1mm resolution or better with PLA and ABS filaments. I have posted pictures of my 3D prints next to actual the blow molded parts and it is difficult to tell them apart https://forums.rocketshoppe.com/sho...736&postcount=2.

The newer model, the Ender 3, is supposedly an even better 3D printer, it costs $199 from the same vendor. I get the filaments on sale at Amazon for $10 to $15 per kilogram. If you are not into learning a CAD program, I also wrote an article on how to generate 3D printer files from RockSim https://www.apogeerockets.com/educa...wsletter476.pdf

Bruce,

I'll check that unit out . . .

I know Chris Taylor . . . I'll shoot him an email.

No, I don't want to have to learn CAD . . . LOL !

Thanks,

Dave F.

David Merriman, a well-known modeler and diver (see: http://www.google.com/search?source...160.4TqoEZK9cBs ) has written several printed and online "How-To" articles on vacu-forming and resin casting (which involve--and can optionally involve, as there are several methods--the same types of molds and techniques that you described in your white paper. I avoided "re-inventing the wheel" in my resin casting by reading his articles. Another trick that I learned about vacu-forming parts came from PSS (Power Scale Soaring [R/C slope-soaring scale glider models of powered aircraft, including jet and rocket planes]):

While this problem seldom occurs in model rocket vacu-formed parts, it can occur in larger ones. PSS modelers (and "regular" scale sailplane builders) often make their own vacu-formed canopies, usually using the male mold process that you covered. PSS models (and many scale model sailplanes) often have green- or gray-painted canopies, to give the impression of transparency (because it obviates the need to include a detailed cockpit interior), while other PSS and scale sailplane modelers vacu-form transparent canopies. Also:

Because the heated plastic sheet--whether opaque or transparent--is pulled down over the male mold, the cooled plastic canopy retains internal stresses that soon form cracks, especially after bumpy landings, even on grass (which can be stopped by drilling holes through the canopy at each end of each crack. But the formation of such stress cracks can be entirely prevented by gently heat-treating the cooled canopy, before removing it from the male mold, as this provides relief of the internal stresses.

I can confirm Bruce's results, having several examples of duplicate Centuri and MPC nose cones, transitions, tubing connectors, and even 5 mm diameter MPC simulated booster nose cones and nozzles from the MPC/AVI/early Quest plastic parts set (used in the MPC/AVI Taurus-1 Miniroc kit), which he 3D printed.