Ah. *blush* I keep forgetting that not everyone has eccentric craftsmen for fathers and friends. Apologies for my tone. But if you specify tagua nut, do it in a round-a-bout fashion. Don't say "tagua nut," say "the carved tusk of a plant" or something else suitably vague.
You don't have to worry. I'll be as obtuse as I can be if that Catch ever comes up: make it a riddle, perhaps. Thanks for the suggestion!
As for the complexity of conjuring an actual physical Klein bottle? 
Alot. The only reason they could get away with it is because, literally, a wizard did it. Even so, forcing an actual Klein bottle to exist in 3-D space? Probably 15-20 at a minimum, depending on how sadistic the GM is feeling.
Sounds like a great start!
Ultimately, the GM would have to have something in mind before making such a Catch, and figure out the narrative purpose.
If the intent is to give a thaumaturgist some screen time, and maybe get some game history out in the open through some RP challenges and conflicts, the spotlight would be on researching and satisfying the ritual requirements, insisting that the PCs spend actual game time on satisfying some of the component needs, rather than handling them with the standard Lore Declarations.
But a clever Catch has its narrative value as well, so the focus of that could be for the players to figure it out without dice rolling (perhaps by solving the afore-mentioned riddle) or to make some connections in new territory (befriend a Quantum Physicist, for your Klein Bottle challenge, an Art Dealer for an art-related riddle, a Demon for some unnaturally accurate information).
But the common denominator would be to make the Catch substance a part of the story, rather than just a Resources check or a Lore Declaration.
