If you are looking for flip or wallet type cases, they are listed on aliexpress.com (search for Teracube 2e). Quite cheap but I cannot vouch for the fit. I do know it may take a while to reach its destination.
Probably the same thing on Amazon. (disclaimer: not affiliated, probably shipping from china)
this is not a specific case for the 3e its just a generic fit one they use for a handful of phones that are the same dimensions. there are also now “aftermarket” screen protectors they specify for the 2e for about 3$ for 2 of them in glass from aliexpress