Here's the machine that printed everything! It's a Prusa i3 home-built reprap printer. There are plans to build it online: http://reprap.org/wiki/Prusa_i3. It does involve some electronics, but it's certainly no more difficult than building a kayak.

Here's a pic of the filament that the printer uses: https://i.imgur.com/TfIvZsp.jpg. The label on that picture says PLA, but i'm recycling the spool. It's ABS. Here's my filament extruder setup: https://i.imgur.com/JvEUqbZ.jpg. The thing on the left is basically a motor driving a auger drill that feeds plastic pellets into a heated nozzle. The thing on the right winds up the filament as it's extruded. I got a big box of recycled ABS off ebay, $25 for 16 lbs of plastic shipped. Hence why the cross sections are so cheap!

I'm actually currently working on the model for the coaming in OpenSCAD. I'm planning to construct the coaming in a very similar way, but with aluminum tubes as joints. It'll allow the coaming to split in half easily.