Until now I have no problems with the spool hold.
I added some pics of the spool hold. Important is the plastic thing that prevents the filament from falling from the spool, and something that holds the filament in direction. I have done a lot of printing with that without problems.

Indeed. At 60°C ambient, which is not unheard of in an enclosure, the Sanguinololu's MOSFETs will derate to the point their Max Current capability is a measly 4.6amps - Just enough for the underpowered 'stock' heated bed but not enough for a QU-BD or custom heatbed.... sure they'll do more still, briefly, but only at the cost of raising the junction temp above their 175°C max temp and letting the magic smoke escape. And even with the stock heatbed - thats the claimed max values according to the datasheet - its not whats recommended for healthy long term operation

So yes, active cooling/venting is needed on those MOSFETs (let alone the Stepper Drivers! I would hate to do the derating calculations on them, suffice to say, it'll be under 20% rating of their already overly optimistic rating at an ambient of that temp... and the temp of the MOSFETs becomes irrelevant if you can't print without missing steps ). Heatsinks alone wont do it, since they only will conduct to ambient, which is still too high. You will need active cooling to ensure prolonged MOSFET life...

Its the sting in the tail in MOSFETs.. they rate them based on a 25°C ambient, and they derate something shocking (compounded by the fact their RDS(on) value can become 2x their 25°C rating, further generating heat and lowering the overall ability for the MOSFET to dissipate power... )

The printer can be rolled out by a ball bearing move out.
The fillament sits on top of the printer with some self made "headset" (like on a bike)