I bought a similar cover (in red). Fits perfectly on the 3 fob.
https://www.amazon.com/gp/aw/d/B07BNZCJXR?psc=1&ref=yo_pop_mb_pd_title
Hot Leather Car Smart Remote Key Fob Case Holder Cover Fit For Tesla Model X /S | eBay
I use a leather one like this for my Model S.
The leather is a much lower profile and is less grippy in the pocket.
They fit extremely snuggly on the Model S fobs so I’m assuming they will be a perfect fit for the Model 3 key fobs.
Ordered for my Wife’s Model 3 in different colors.
eBay is nearly half the price over Amazon on these. Many sellers...