I created a character that is a martial arts/wizard mix who uses fists to cast spells. The reason behind this is, that he is using the moves he learned from his training to focus his mental energy and create the effects he wants. Of course those effects mostly require him to be able to touch the target. I did this by giving him a stunt that lets him use fists instead of discipline for casting spells, if he can touch his target, simple as that. He is greatly limited in "normal" spellcasting of course.
However, if you want to replace the lore skill, that is going to be tricky, because it is the skill that let's you know how magic works. As I understand it, you want to use it for thaumaturgic rituals, and if you limit it to that, I don't see a reason not to do it. You can argue, that the characters wizard senses are tuned to colors and forms, so he can see the magic as patterns of colors he can create or change. Preparing a thaumaturgic ritual would not only consist on gathering materials, but also creating paint out of that material. So it would be a stunt (or much rather an addition to a supernatural power) that allows you to use crafting instead of lore for thaumaturgic rituals. You should also take an artists stunt to represent your expertise in that area.
