There's some info about it here https://reprap.org/wiki/Mendel90

This is a very old printer, from the early days of reprap. From a practical standpoint you would get better results from the cheapest new ender i3, and it would be a lot easier.

If you want an interesting project though it should be entirely possible to get it working, and you'll learn a lot from it. If it's still using the original Sanguinololu controller board that will be your biggest issue, as I doubt a modern version of the marlin firmware will fit in a ATmega644P. Your best bet would be to replace the controller board with something modern, then you can use it as any modern 3d printer.

Even if modern slicers have gained a lot of advanced features, to my knowledge the gcode they output is still very simple. You can put all kind of fancy commands in the start and end gcode, but the actual printing part consists almost exclusively of commands that move the nozzle to a specific XYZ coordinate, and/or make the extruder motor move the filament either backwards or forwards.

Maybe ask your brother about what software he used it with? If the printer has an sdcard reader it might be easier to print off that than try to get it to communicate with a computer. I don't have any first hand experience with that old printers, but I would guess it uses some kind of serial over USB protocol similar to modern printers. If you're using Windows I think you might need to track down a driver for the printer's serial controller, but if you have Linux there's a chance it has the necessary drivers built in.

Of course. Especially those DIY printers are pretty resilient to aging. I have Anet A8, one of the early ones, that has been through so many changes it's far better than most new printers these days. If you are into it, go ahead it will be a fun project.

Never heard of that one but old printers, if in good condition, work just fine They might not understand some of the newer gcode commands but that's only a few Nero3D streamed a three-part series where he assembled and use an original Ultimaker from 2013 Barnacules Nerdgasm used a similar Ultimaker to print parts for a Voron 2.4 build Still very capable printers

You can start by creating a custom machine profile in Cura (or any other slicer) with the appropriate dimensions for your machine and start from there. It should work, but you will probably need to do a bit of calibration afterwards. Or you can start from the profile of a similar machine and tweak that

Everybody, thanks for all the help. After a whole lot of fiddling I got the thing to move, just to find out that it expects 3mm Filament, which is not sold at my local store. So faced with replacing the hotend and extruder I gave up and ordered a kp3s pro for less than 100€, maybe my first printer should be something that actually works.

3d printers haven't changed that much. If you can get some info from your brother and he can tell you what might be wrong (if anything) that would be very helpful.

Modern slicers can work with anything. At it's core all printers simply run on G-code which is itself just a series of coordinate instructions telling the printer where to move the head. As long as you have the right sets of startup/configuration codes (which should be trivial to find online for any open-source project printer like the Mendel90 using the standard controllers of the era) any slicer will work with it.

Looks like the original project files made by Nophead are still available.

Good enough to get you started. For day-to-day use you might want to upgrade to a modern design.

software? Could be Repetier host (never used it so but I know that it was common back in the day): https://www.repetier.com/download-now/

now that is helpful, how did I miss those. I'm excited!