What's the most difficult mod you've ever attempted?
Thinking of my failure with this puzzle, it is the Siamese Skewb. Some kind of shame.
What's the most difficult mod you've ever completed?
That would my Cheops Cube or the Professor Barrel: A Nintendo Barrel with 4 Layers.
In your opinion, what's the easiest mod to make? (excluding sticker, direct piece swapping and bandaging variants)
You know that you are excluding two thirds of my self-built collection?
In that case it is the Extended 3x3x4.