I decided to use the Glowforge to engrave some designs on a leather belt, but without a passthrough slot I needed a way to wrap a long belt around inside of the machine (which you can't do with the crumb tray inserted). This jig is my way around that, allowing for clips and masking to hold the belt flat while also allowing the extra to curl around underneath out of the way.

• Cut all parts out of 3mm material and glue together (I glue the clamp cuts to make a 6mm thicker/stronger version)
• Remove crumb tray from Glowforge and install the jig.
  • Center it as best as you can against the inside front of the device (it's almost exactly 80mm from each inside edge of the opened door)
  • I leave a piece of masking tape in place as a reminder for the left-most edge to make it easy to reinstall
  • I also tape the jig to the frame of the Glowforge so it doesn't wiggle around.
  • Don't install the leather yet, but put a couple squares of masking tape at each corner of the jig.
• Drag the Glowforge alignment lines.svg into GFUI.
  *Mark the larger pinkish lines to be ignored. These contain blocking for .5", 1" and 1.5" alignment (everything else is in metric, but my leather straps are all in inches).
  • Score the smaller green squares at 0.1 thickness (GFUI won't let you do zero) at 1000/2 -- they should end up 1mm away from the back edge and finger joints in the "bed".
  • Adjust your jig placement as needed, or edit the Glowforge Alignment sketch in a copy of the Onshape document (I'll leave it to you to re-export/color/convert it)
• Once you're aligned:
  • Feed the leather into the holes, clip it in, apply masking (it helps a LOT for etching -- only the last 2 in my photo were masked with almost identical settings to the other versions)
  • Line your engraves up with the appropriate guide lines
  • Make sure ALL of the guide lines are set to "ignore" (I left my mistakes visible in the photo as a warning).
  • Engrave away! I've been having good luck with 300 zooms and 10-12 pews for masked leather (TransferRite Ultra), and 250/6 for un-masked.

You can find the original CAD source at OnShape if you need to re-export or see the assembly in more detail.