Portable RepRap for demonstrations

I recently attended the Midwest RepRap Fest (MRRF 2014). In talking to a few of the other attendees, I noticed a couple of themes. A lot of us do demonstrations of our printers and those who flew to the event didn’t have their printers along.

2 RepRaps and a ROMER laser scanner
This is what I brought to the event. 2 printers, a ROMER arm laser scanner, 2 computers, 3 tablets, my portable robot making fastener kit, some clothes, and a case of soda. Filled the back of trucklet right up.

This tells me that there is a need that has yet to be fulfilled. The hobby needs a small, portable printer.

Just push hard, it will fit, right?
I think having a 3d printer that can fit into a carry-on bag isn’t too much to ask.

OK, that would be a REALLY small printer, that can take a bit of abuse, being banged around inside a carry on bag.

Water Cooled Maker Gear Prusa Mendal RepRap with a tablet using GCodePrintr
This is my ‘small’ printer. That’s a 7 inch tablet running it in this photo.
RepRap in a case
I have this HUGE case that JUST fits my printer.

So, on the way home, I put some thought to the problem.

We need a printer that is:

  • Able to be held in one hand for demonstrations
  • Able to fit in carry on luggage for travel
  • Able to run while ‘unplugged’ if just for a short period of time
  • Visually interesting and has all the parts exposed so it’s easy to explain how it works


I picked up a SmoothieBoard at the show, so I want to run it off of this new-to-me board. It seems to be one of the larger boards, so other boards could be dropped in if desired. It has a built in microSD slot, so it can print without a controller. It also has lots of extra horsepower so it can do some crazy cool stuff.

Looking around, at MRRF, I saw the Tantalus. A nice, small, box printer, but not small enough. I also saw the Wally.

Then it hit me, what if I was to put a Wally inside a Tantalus. Shrunk down. The magic is that the Wally can extend outside of it’s containing ‘box’ while in use, but ‘park’ within the confines for safe traveling.

BOOM! I can print a larger print in a smaller space.

Wally at MRRF 2014
Meet Wally. So named because it’s a ‘wall’ printer, everything is built off of the back wall.

I think Wally is a slick printer. It’s built with plastic parts, common bolts, and not much else.


Wally's Z Stage
This the Z stage. It travels in an arc as it goes up and down. Crazy simple mechanically, and it makes my brain hurt doing the math on it even though I know it’s a simple offset.




A few minor tweaks and I think a Wally can be crammed into a small box. The Z can come out of the front view port while printing and the XY arms can extend out the sides while printing.

The Z arms need to be longer, poke through the back, and bolt on with the mounts towards the inside so we can get the max width print bed on the inside of the printer.

Everything needs to scale down a bit. From my reading, there needs to be a 7-10 ratio between the pulley on the motor to the big pulleys. There is also some ratio for the arm length to the big pulley size, but I don’t understand that yet.

All the motors should hang off the back I think, just so there is more viewing room inside the box.

I am thinking a 150mm square box would give me enough room to route wires cleanly off of a smoothieboard.

A small battery can sit under the print bed. I am thinking the power supply should be a generic laptop power supply. This keeps the printer smaller and lighter, not having to mount a power supply in it. This would also allow us to unplug the printer for short periods of time to walk around with it.

Mulling the idea around a little bit before I create a fork of Wally and start wrenching on the parts hard.

I think a lot of people will complain that it will be TOO small to be useful. It’s not intended on being an only printer, it’s a functional demonstration piece. Long (large) prints aren’t useful for demonstrations, it seems like they are only half-done when you want to pack up and leave. You want to be able to spit out a part in less than half an hour and have people hold it.