Lego Ruler

Way back in 2009, Lego released a set called "Designers' Tool Set" which had a brick separator and a rather cool triangle ruler.

They unfortunately don't make this anymore and getting hold one now on the second hand market will set you back $40 or more even if you can find one.

Until the day that you can find one, here is a copy I hacked together in onshape.

If you want to buy an original, the set number is 852690, part number bb0342.