Teachergeek.com is a maker company that sells kits and individual pieces to inspire innovation. You can find ideas for science, technology, and especially engineering.
Teacher Geek is great because it’s inexpensive and they provide free curriculum with easy to follow instructions. On first sight the product seems to be geared toward early elementary to middle school but the product can challenge your most advanced makers. For your advanced makers, set out various pieces along with tape; cups; rulers; cardboard; etc and give your makers a directive without instruction.
Another pro is that the possibilities are endless.