ARC back panel mods: tensioner access and chamber/stepper cooling fans

This design modifies the ARC rear panel with cutouts for access to tensioners without removal, and adding chamber/stepper cooling fans. PDF and DXF format cut files are provided in the downloads.

Pre-cut acrylic panel kits are available from my Etsy shop here: https://www.etsy.com/listing/1394686261/acrylic-panel-set-for-bambu-p1p-arc

Access to the tensioners will be useful as the belts age and stretch, and require re-tightening beyond the capacity of the auto-tensioners, or for complete belt replacement. Instructions for the tensioning procedure are here: https://wiki.bambulab.com/en/x1/maintenance/belt-tension

Fan cutouts are designed for 40x10 or 40x20mm fans, either should fit without any clearance issues to the belts or head motion path.

Fans can be installed for intake or exhaust, I've also included a file for a modified fan grill which directs ¼ of the fan flow directly onto the X and Y axis stepper motors (the motors can get VERY hot during long prints), which should prolong their life.

If you're using high flow fans, you may want to install in exhaust orientation to prevent overcooling of the print area, low flow fans like Noctuas should not present an issue.  Alternatively, I've also added a louvered design which should work with high-flow fans to direct the incoming air away from the print area, and alleviate over cooling, but I have not tested it yet.

Chamber cooling should be used with PLA prints to keep the enclosure temperature below 35C, temperatures above that may encounter heat-creep related extruder clogs.  The position of the fans is intended to exhaust hot air or bring in cool air in the critical region around the print head to keep the temperatures around it low while allowing the top and door to remain closed to decrease noise.

24v 4-pin fans can be connected directly to the chamber fan header on the control board and activated in the start gcode by adding: M106 P3 Sxxx (where xxx is a value between 0 and 255 to control the speed of the fans via PWM)