You might have found this thanks to the Tested YouTube video with Adam Savage, it's because of that video this thing exists ;)
The "Universal Greeblie" used at ILM, from the model kit WWII German Leopold rail gun in 1/72 scale.
Single, and as a "pack of three".
You most likely need an SLA-printer for this one, since it is less than 7mm big.
I have yet to print it myself so no guarantees if it is exact to scale or if its hard to print.
EDIT: Per request I added booth the single and the 3-pack with flat bottom, and the 3-pack flat bottom angled 45 deg for easier FDM-printing.