I've only been making courses for a few days now, but I really enjoy making short challenge courses.
9248-0000-0057-842F Leap more
8B24-0000-0059-166B Dangerous Parkour
9A38-0000-0059-3051 "No, Ed!"
4A97-0000-0059-5DFD Spring Ninja: Easy
8AB4-0000-0059-6120 Spring Ninja: Hard
6DBD-0000-005D-3F81 Leap further
The only one that's mean/unfair is "Leap more", because it has Lakitus. The rest are beatable with timing/skill.