Arcane Ablation

You touch a  piece of worn armor or clothing and imbue it with magic. The creature wearing that item gains 5 temporary hit points. When those temporary hit points are exhausted, at the start of the creatures next turn it will gain one less temporary hit point than the last amount of temporary hit points it had from this spell. This will continue until the number of temporary hit points you would gain would be zero, at which point the spell would end. (Note, you will have to key the temp. hit points in yourself)

At Higher Level: the initial temporary hit points increases by 1 for each spell slot level above 1st. 

(This is the same spell from Artificer 1.7, you can find more good homebrewed Artificer stuff from it just google it)