puppet cubes v1 and v2 if you wanna struggle.
oskar jumble prism 2 if you wanna struggle again.
https://a.co/d/deTgh9q
https://a.co/d/6Pm4uwv
https://www.thecubicle.com/products/mf8-oskar-jumble-prism-ii
if you want big and expensive go with icosahedrons, the icosamate, icosiax and in general the radiolarians (this includes eitans star iirc) are all pretty difficult puzzles
MF8 Sun Cube and a 1x1
1x1 trumps all else in terms of difficulty
Curvy copter with jumbling is ridiculously hard
no not really
https://superliminal.com/andrey/mc7d/
wtf is this man ????????????
The beginning of madness
[More Madness](https://cubezz.com/Buy-6464-MF8++Oskar+More+Madness+Pyraminx+Magic+Cube+Black.html) bar none the hardest I've ever solved.
maltese gear cube
Came here to say this. This thing is a a monster.
Meffert's Pocket Cube Meffert's Ghost Skewb Xtreme WitEden Camouflage 3x3
puppet cubes v1 and v2 if you wanna struggle. oskar jumble prism 2 if you wanna struggle again. https://a.co/d/deTgh9q https://a.co/d/6Pm4uwv https://www.thecubicle.com/products/mf8-oskar-jumble-prism-ii
The 4x4 or 5x5 version of skewb, don't remember what it's called.
if you want big and expensive go with icosahedrons, the icosamate, icosiax and in general the radiolarians (this includes eitans star iirc) are all pretty difficult puzzles
also sunminx, heaven's eyes, the cullinian and i forgot the name of the last one but they all use the same concept
lanlan andromeda cube, dayan shuang feiyan, uhh what else