A 120 mm cube of build volume sounds like a toy. It is not: it is the smallest enclosed print space that will still hold most of the small functional parts people actually need, and enclosing a volume that small is dramatically easier and cheaper than enclosing a large one. That is the whole argument for this machine, and it is a better argument than its size suggests.
Three hours, three cents
A 35 g ABS part, 3 hours, filament at $28/kg, machine time at 20 cents an hour and a 5% failure allowance:
- Filament: 98 cents
- Electricity: 3 cents, from 0.18 kWh
- Machine time: 60 cents
- Failure allowance: 8 cents
- Total: $1.70
Three cents of electricity for an enclosed ABS print. Every intuition that says a heated chamber must be expensive to run collapses at this size, because the thing consuming the power is the plate, and this plate is tiny. Check it against your own tariff in the cost calculator — even at the dearest rate in the regional table, the line stays in single-digit cents.
The wattage behind it is a class estimate rather than a plug-meter reading, and on a self-sourced build it varies with the builder's choice of bed heater and power supply. At this magnitude that uncertainty is irrelevant: three cents could be double and still not matter.
What a 120 mm chamber is actually for
Small enclosed printing is not a compromise; it is a specialty. The work it does better than a large machine:
- Printer parts. The community design's own printed components are all small ABS parts, and this machine exists partly to make them.
- Brackets, mounts and adapters in ABS or ASA that need to survive a hot car or a warm loft.
- Small mechanical parts in filled nylon, where the fibre and the warm chamber together make a genuinely strong component.
- Anything you need while your big printer is busy. A second machine that costs almost nothing to run pays for itself in scheduling alone.
What it emphatically cannot do is anything over 120 mm. There is no clever way around that, and splitting parts at this scale usually costs more in fasteners and glue than it saves.
Fast, because it is small
The moving mass on a machine this size is trivial, and the distances are short. That means high accelerations are achievable without the frame ringing, and short travel moves complete almost instantly. In practice a small part often finishes faster here than on a much larger, nominally faster machine, because a large machine spends its speed on travelling across a plate that is mostly empty.
The limit, as everywhere, is melt rate rather than motion. The print time estimator makes the point plainly: once the requested flow exceeds what the hotend can liquefy, raising the speed setting changes nothing at all.
Building one
This is a self-sourced community design, not a product. You need printed parts made on another machine, a bill of materials or a vendor kit, and the willingness to be your own support. It is the smallest and cheapest build in its design family, which makes it a common first build — and a common second printer for people who already own a large one.
Because it is self-sourced, every specification on this page is a description of a typical build rather than a manufacturer's promise. Two correct V0.2 builds can differ in hotend, extruder, board and bed heater.
Problems that come with a small chamber
Heat soak reaching everything. A small chamber warms up quickly and thoroughly, and there is very little distance between the plate and the toolhead. Heat creep is the characteristic problem of small enclosed machines, and keeping cool air fed to the hotend heatsink is the whole solution.
Cooling PLA is awkward. A warm small chamber is the worst place to print a material that wants aggressive cooling. PLA works here, but overhangs are better on an open machine, and running with the door open is a legitimate answer rather than a defeat.
Everything is close together. A part that comes loose in a 120 mm chamber has nowhere to go and will meet the toolhead quickly, so nozzle hitting the print escalates faster than it would on a big plate.
Why this should not be your only printer
Printing anything large rules it out, which covers most people most of the time. A first and only printer rules it out too — a small enclosed machine is a specialist's second tool, not a generalist's first. And wanting to buy rather than build, for whom a small factory-made enclosed machine will be far less trouble even if it is less interesting.