Which Raspberry Pi to get?  

Pi zero 2

Pi Zero 2 might be the best choice.  

RPI Zero

Pi Zero you can directly connect to printer see https://help.prusa3d.com/en/article/prusaprint-rpi-zero-and-octoprint_2180 without occupying the usb port.

zero

If you can get it to work...Thus the reason Octoprint recommends the new version 2.  

Posted by: @zoltan

Pi Zero you can directly connect to printer see https://help.prusa3d.com/en/article/prusaprint-rpi-zero-and-octoprint_2180 without occupying the usb port.

I use 3b+ Pis. Tried and true. 

I use 3B+ as well

I am thinking of trying to set up the new one if it is cheap enough.  Avoid the RPI zero if you want to run octoprint.  The zero v2 is just out - so no track record - experiment a bit.

The MK3 is designed to accept a Pi Zero internally - unfortunately, whilst it still works as designed, Octoprint has moved on considerably since then and the plain Pi Zero can no longer keep up unless you switch off most of the new features.

The new (this week) Pi Zero 2W has precisely the same footprint and so is a drop-in replacement.  It is functionally more or less identical to a Pi 3 which is generally recommended for the job (but doesn't fit the case).

I understand the software does run on Pi Zero 2W but the board is so new that it hasn't yet been comprehensively tested.  It's safe to assume that even if there are issues they will be addressed promptly as Octoprint are actively working on it.

Cheerio,

Pi 4

Just get a Pi4 if you can find one.  Quite in short supply these days in my area - can't find any Pi at MicroCenter in Vienna, Virginia - 'cept for the 400 keyboard thingie.

A 2G Pi4 on sale can be had for $25 bucks.   4G, maybe $10 more. Not sure why you would want to save the USB port.  Really?  For what else?  Inkjet printer?  Dial-up modem?  Headphones?

Pi4 will do everything you need today - including camera - including multiple cameras if you are so inclined.  It will also do everything you need tomorrow.  If a Pi Zero 2 is like a Pi3, a Pi4 blows it out of the park.  Over time, PrusaPrint, OctoPrint, and whatever else will just get piggier.

IMHO don't even think about either a Pi Zero or trying to power the Pi from the printers PSU

IMHO don't even think about either a Pi Zero or trying to power the Pi from the printers PSU. The price of a Pi4 will give you load of room fro expansion and is probably costs less than a reel of filament. Pi Zero2 W is an option if you don't need headroom and you want something small.

Pi4

I concur with a Pi4.  I have reviewed the Zero 2 but see no reason to change.  

Posted by: @towlerg

IMHO don't even think about either a Pi Zero or trying to power the Pi from the printers PSU. The price of a Pi4 will give you load of room fro expansion and is probably costs less than a reel of filament. Pi Zero2 W is an option if you don't need headroom and you want something small.

Thanks for the advice!

Thanks for all the advice, have decided to order a Pi4.

Not a lot of supply here in Norway right now - but managed to find a 4GB Pi4b.

Read somewhere that these tend to run somewhat hot - should I get heatsinks? fan? Any specific ones I should consider?

Pi 4

On my Minis, I use an aluminum enclosure with a fan and heat sink.  On my mk3S, I just use a heatsink.  

Posted by: @printerman-2

Thanks for all the advice, have decided to order a Pi4.

Not a lot of supply here in Norway right now - but managed to find a 4GB Pi4b.

Read somewhere that these tend to run somewhat hot - should I get heatsinks? fan? Any specific ones I should consider?