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document updated a month ago, on Jun 13, 2024

constructing a straight-edge

There are a lot of details below, but in summary, this is how I prefer to make one:

material Only steel is acceptable — aluminum is softer than a steel utility blade, so is liable to being scratched, allowing the blade to climb and travel over the straight-edge, posing a hazard to your fingers.
width 1½" is great, and 2" wide is acceptable. 1" is probably too narrow, as it doesn't give enough room for fingers to keep the straight-edge steady while avoiding risky situations with the knife.
thickness 3/16" thick is much better, though ⅛" thick can work too. (0.1875" or 0.125")

What I learned is that the heavier, the better, because this helps keep the straight-edge in place.

anti-slip backing — thickness I like varying thicknesses:
  • 1⁄16" thick (often available with adhesive backing)
  • 1⁄32" thick (often not available with adhesive)
  • workout resistance bands — somewhere around 1⁄64", but your mileage may vary

Thicker rubber can accommodate bumps and protrusions with ease, but feel like they would be less accurate due to the fact that the straight-edge can rock side-to-side. If possible, the rubber should be firm, especially for the thicker pieces.

Note that you can put different thicknesses of rubber on each side of the straight-edge, which gives you a choice of which one you want to use for each cut.

anti-slip backing — material You want THE grippiest material you can find.

I've had luck with rubber that describes itself as "Buna-N rubber", AKA nitrile rubber. [1]

Supposedly silicone is the grippiest rubber available. Bonding silicone isn't the easiest; here's some advice. (Worst case — either use UHMWPE to "stitch" the silicone onto the steel, through holes in the metal; or find a way to cure raw silicone in situ against the metal, known as 'overmolding' or 'insert molding')

adhesive I tried super glue, and it sort of works, but it had decent-size sections that didn't adhere properly. 0/10, do not recommend.

Maybe try contact cement?

Rubber that is manufactured with adhesive on the back is great, it's much simpler/quicker to use than using your own adhesive.