Cutting US Letter Paper
The Pepakura Viewer for CraftROBO's support for US Letter and US Legal sized paper is slightly broken. Until a future update fixes that, here's a workaround:
1. The source PDO file should be set to ISO A4 paper size in Pepakura Designer 3.
2. Change the registration mark margins in the Pepakura Viewer for Craft Robo to the following settings:
Top: 25mm
Bottom: 32mm
Left: 15mm
Right: 10mm
These settings will shrink the development area so that the cutting area will fit on a sheet of US Letter paper. Next, open the PDO file in the Viewer, configure your printer to use US Letter paper, then use the Print Preview function to check and make sure all of the developments fit within the registration marks. If any of the developments do not fit within the cutting area, go back to Pepakura Designer 3 and adjust their positions. (The grid and snap line features are very helpful for this.)
Print the PDO file on US Letter paper.
When you cut the developments, make sure the CraftROBO is set to use A4 sized paper. This will prevent the incorrect scaling and positioning bug that you'd otherwise have to put up with. (The way this workaround deals with the issue is by fooling the software into thinking you're using A4 paper.)