The Fix-It Tool Box from Hape Toys packs nuts, bolts, and all the tools little builders need to tinker into one ready-for-action case.
My three-year-old carries this case around like a real handyman and the tools finally have a home instead of being scattered across the floor. The nuts and bolts are chunky enough for small hands to grip, and everything snaps back into the case when we're done.
The little bolts actually screw into the nuts, so my son isn't just pretending—he's really tightening things. Everything clicks back into the case when he's done, which saves me from stepping on stray pieces.
The little wrench actually unscrews the bolts, which keeps my 5-year-old busy for a solid half hour. Everything stores back in the case so we're not hunting for pieces under the couch.