Well I’d say your audiologist will recommend which is more suitable for you, there’s many more that can be considered, , the full shell and skeleton types not only allow for severe profound losses,they also don’t move around or come loose which would give feedback issues at high gains, even the canal lock types are good at this as well, pity it takes so long to sort out, the usual time frame would be 2 weeks, 3months to too long, you could get them done yourself, but a little bit of risk if they don’t fit correctly and have to have them remade!
There’s been a bit of discussion on making your own on the forum,this is one of many ,check it out.