For the sake of completeness and for future readers, here's the solution I was able to create for this issue:
From the drawing of the bent metal example that I uploaded earlier:
- In the Parts Design WB:
- create a new sketch, choose the YZ plane (vertical, slicing down through the part).
- Use the Exterior Geometry tool to select the 'interior' face before the fold (the portion of the part that's horizontal on the XY plane)
- Create a vertical line on the YZ plane constrain the bottom point to the 'interior' face, and set it's length to the desired height, in this case 7mm.
- Again with the External Geometry tool, select the interior face after the bend (the face above the horizontal face, at a 120 degree angle), and constrain the upper point of the vertical line to coincide with this plane. That should fully constrain the vertical line
- Screenshot from 2022-01-23 13-06-50.png (11.22 KiB) Viewed 218 times
- Select the upper interior face again and create a new sketch. This will create the new sketch in the plane of the upper, bent face. Use this face to locate a hole, referencing the edges of the upper plate, or create a horizontal construction line to reference an array of more than one hole.
- Screenshot from 2022-01-23 13-13-13.png (12.51 KiB) Viewed 218 times
Hope this helps. Thanks for all the suggestions, that got me started on this solution.