After a couple years of fantasizing about owning one, I finally took action month before last.

I built a Prusa i3 from parts, single-sourced everything as a kit from RepRapWorld.com; that's more expensive, but much more convenient when you don't know what you're doing.

I didn't count the hours but it probably amounted to a couple weekend's worth of full-time days, all told, most of which consisted of tearing down and rebuilding something I'd already done which didn't quite work. Even so, the mechanical assembly was less trouble than the electronics - I plugged something in the wrong way and ended up blowing a fuse on my electronics, then blew a power supply while trying to "fix" that. Fortunately RRW were extremely helpful, I shipped the board back to them, they fixed the fuse and sent it back to me.

If you're not already well equipped for shop type work, remember to budget for tools.

Next time, if there is a next time, I might try the other popular approach, scavenging parts from discarded printers etc. to keep the costs down - and make the project even more challenging and time consuming!

I wanted to interest my kids (12, 15 and 18) in the project but that part didn't turn out as well as I'd hoped.

Once you've built the thing, there's still lots to do: fine-tuning, upgrading (for instance leveling the print bed is a pain in the ass, so I'm considering buying parts for an automatic leveling add-on), trying fancy plastics, and so on.

One unexpected difficulty was calibration. It's one thing to get the various parts working, to have the extruder actually extrude plastic and move around in the X,Y,Z axes - but to print objects you also need to choreograph all these motions just right: to move the right amount of X and Y while the extruder spits just the right amount of plastic. This requires repeatedly fiddling with the source code for the firmware and uploading that to the Arduino compatible board.

I'm still at this "tuning" stage right now. The first few days were heady as I went from "printing" a blobby mess of plastic thread, to a few decent-looking pieces. It's more of a grind now, as fine-tuning involves lots of guessing what could lead to an improvement, doing a print, and starting over; and these machines are SLOW.

Whether I can do something "actually useful" with it is still an open question. Even printing replacement parts still looks like it could be a challenge, there are so many things to get just right if you want parts that don't break, that print at the exact X,Y,Z dimensions, and so on.

I'll be honest, I'm now past the "honeymoon" stage where these difficulties were delightful, and experiencing some frustration, in particular at the slow speed of iteration. I'm a coder, I like being able to test tweaks in a matter of milliseconds. But that was the point - to get out of my software comfort zone and do something substantial involving hardware.

I've backed the Peachy from Kickstarter and hope to receive that in the next few months, it's a totally different principle (stereolithography like the FormLabs, but with many tweaks that keep the cost way down).

Building your own is a great experience, and whether I keep at it or not, I'm glad that I invested the time and money; now I know exactly what these machines can and cannot do, which gives me a great perspective on the hype from mainstream media and evangelists.