Thaumcraft Aspect Creator is a Forge mod for Minecraft 1.12 that is able to load user file-defined aspects into Thaumcraft BETA 26.
The mod is mainly oriented towards modpack makers and won't provide any item with custom aspect, nor any use for them. To add functionality other mods like Crafttweaker / Modtweaker are needed.
Thaumcraft BETA 26 is required, and Just Enough Items / Had Enough Items and Resource Loader are highly recommended.