I’ve seen genuine key case for my RRS TDV6 on duckworth parts.

Is it easy to swap cases?

Also what battery do the keys take?

I bought 2 cases, had to use the guts from my damaged keys in the new key cases. Pretty easy, about 5 mins per key. Just strip the old one out as if you were doing a battery swap. Then I used a soldering iron to melt the plastic tabs off the posts that hold the circuit board in to the case. Swap the guts over and use the soldering iron to melt the posts and form the new heads to retain the circuit board. Reassemble and test on the car. 2019 5.0 SC SVA (Current)
2012 5.0 SC AB. Sadly written off by a campervan
23 plate Focus ST (Current)
1942 VEP Ford GPW Jeep (Willys) (Current)
1943 Whites M16 Halftrack (Current)
16 plate Eurofighter Typhoon, 2 x Eurojet engines with 20,000lbs thrust each. 1380mph

There are two different cases for the facelift RRS1 Vin. No's AA212145 up to BA717905 (LR052905) and CA000001 up to DA806522. (LR078921 Matt) & (LR059383 Shiny) I don't know if the earlier internals will fit directly into the later smaller case though, although if you look through the wanted section I believe there is someone who is offering this mod to upgrade to later key fob. There are actualy two different cases for the later fob although totally interchangeable one is just a matt black rough finish the other is a smooth black finish almost like piano black. I changed mine a couple of years ago and used the matt black one's, as the lacquer on the original shiny one's was actualy flacking off and looked very tatty.

Cheers
Col

Thanks for the response guys I have just dropped him a PM