Here's a challenge I posted for the lads at work:
Model a hyperbolic, paraboloid-shaped, stack-able potato chip. AKA a Pringle.
I don’t have a chip to reference for dimensions. Instead I found this site that measured some chips for a project: https://www.slideshare.net/brauer3047/pringles-2
Slide 17: 2.5” long, 1.5” wide, .75” tall, 1/16 thick
How It’s Made has a short video showing the manufacturing process. It won’t help you with this challenge but who doesn’t love a reason to watch How It’s Made?
https://www.youtube.com/watch?v=_pVhkgYUgo0
Here’s a stack of twenty of my chips:
SW2020, two simple sketches to build surface, it took me 5 minutes (with tea and coockies). Dimensions are free, I don't think they are important.

I like the texturre
One challenge of creating a challenge is to make it not too complex or involved.
If a challenge take more than 30-60 minutes to complete few people will participate.
Most "challenges" are easy to solve IF you know the needed tools/steps.
Most of the folks I work with make rectangular blocks with holes in them. They've never used a projected curve. This challenge teaches them a new tool.
If you solved this quickly or found it too easy it's because you already have the skills to make it. It can't hurt to practice those skills once in a while.
I appreciate your replay and understand it but I was not asking for complex one I just ask for creative one that can be easy in drawing but have creative thinking ....again thx alot for everything and your good work
Always thought that challenges are createn to show your skills.
I think that i can draw everything what can be drawn by CAD and if i see new challenge i will participate because i want to proof to myself that i can. People don't participate challenges because they are not interested or too lazy to do it.
Of course, for beginners this is not a challenge but a lesson, but what prevents you from learning to draw more complex things.
How many did this as a true hyperbolic paraboloid?
My dimensions for the straight edges were picked at random because they looked about right. Turned out to provide close to the correct thickness given the length and width dimensions.