I like Krogoth's scheme with the encrypted/ password protected private-key.
Adding a password would prevent the maker from sweeping the balance of funds.
Problem is the collectable can not be sold on the secondary market with the passphrase attached.
- - - - - -
There are alternatives to the Trezor signing device that may be more preferred.
I may write more on this topic in the future.
- - - - - -
Thanks! I am looking forward to other peoples ideas on this as I am sure there are and probably better. So please yes do post and let us know what your ideas are as I have thought of many different ways to prevent any future Shitkey scenarios!