The most secure trusted way to create keys for physical coins is to get Satoshi to do it.....End User produced keyed coins have no resell value as a collectable. If your looking to get into producing collectable coins.....even untrusted producers can create keyed coins unfunded and leave it up to end users trust level of the producer if they want to fund them or not.... are you looking to produce a secure place for people to park their bitcoins or are you trying to produce a novelty collectable....IMO it's either one or the other...