Making a "D" shaped hole...

[N1VSM]

I'm looking at (finally) installing some parts that go in a "D" shaped hole. My question is how to make a hole shaped that way? I know the *real* answer is to buy the right Greenlee punch-out, but considering that I'm going through heavy gauge steel - as thick as M37 body, and that I would have to sell the truck to afford the tool ...

My idea was to drill the correct size hole and then use a file. Are there any other less brutish ways?

[Lifer]

I imagine the "drill and file" method is probably your only option without the punch. I've made lots of "D" holes that way over the years. (I didn't even know there were punches available.)

[pfrederi]

I know the steel in a M37 is heavier than a M151 but I caught some of my motor monkeys making holes in the Jeep to mount an antenna using a pick axe. It makes sort of a D shaped hole

[monkeymissile]

not sure what size holes you need to make, but a simple template and a plasma cutter could work and require only minimal cleanup afterwards with a file