Lots of people have attempted to design and build fold-up 3d printers, many of which turn out quite compromised.

Now I have seen the first that looks properly competent, and erects into something that prints well – I am guessing at least as well as ~£500 printers.

It is a one-off by Kralyn3D, called the Positron, and fits into a filament box when folded – so around 200 x 200 x 100mm – while printing objects up to 175 x 165 x 125mm

For very good reasons, described in this YouTube video, it prints upside down – with Kralyn3D demonstrating effortless bridging and support material handling with objects sliced conventionally in Cura. Bridging actually looks a little better than I am used to seeing.

It does use the H-bot mechanism for x-y movement, prone to ovalising circles unless x-y motions are well constrained. Most impressive.