Many teachers' favorite store is their local Dollar Store. I personally am willing to spend a little of my own money for a great lesson plan.
The Design Challenge idea is not new, but has gained tremendous momentum with the increase in STEM education focus over the last few years.
These challenges force learners in to a growth mindset but requiring multiple trials, being creative with limited supplies and by relying on group members for suggestions.
I typically handle these challenges with very minimal instructions. A few safety guidelines ("Don't run with scissors!",) show them where the supplies are, and let them go.
Mindset can be further nurtured by putting time limits on the challenge that you know are not long enough. It forces learners to think quickly and be alright with failure early on. With multiple timed sessions, they will improve their design and see the value in not getting hung up on too many details before beginning to build.
These challenges can many times be used to meet a variety of standards including:
Social Studies - how do inventions affect society
Science - Matter and Motion, Physics, etc.
Math - Measurement and Data Collection
LA - Discuss your successes and failures with the class.
Using materials that can be found easily at any dollar store, help foster STEM thinking processes and inquiry based engineering mindsets.
Educators...use the time limits to also force learners to work on on developing a growth mindset. The limits will not allow them to spend too much time on design and more time on trial and error.
You can modify the activity to collect more data by forcing learners to "buy" their materials with a set limit of funds.