Looking for a peculiar, novelty die

[Capt Spanner]

Does anyone know where I could get a d20, but all the sides are 1s?

It will exist purely for comic value. For example: a player insistent on trying something impossible will be told "okay, fine, you can try, as long as you can do it with this die". Or similar.

[DeTess]

A quick google search showed up this site: http://www.chessex.com/Dice/Custom_Dice_Home.htm that makes custom dice, so you could contact them about it. It's probably not going to be cheap though (the Reddit thread that suggested this one had someone mention they had a custom D20 made for about $25).

[Joe the Rat]

Fan of Grand Line 3.5?

[Jophiel]

I'd check Etsy or Shapeways for a 3D printed die you could get done custom. Be cheaper and obviously the die balance won't matter

[Grod_The_Giant]

Find a d20 that has non-embossed numbers, some spray paint, and a sharpie?

[Maat Mons]

They make blank dice of all types. you just need a way to stencil numbers on.