Electric slot car racing sets...these were the coolest and it would keep us entertained for hours since you had to put it together, play as long as you wanted and then we had to put it all away and make sure it all fit back into the box!
Slot cars... I had Scalextric as a boy. It lived in an old leather suitcase under my bed. Now my boys and I have a permanent setup on the mezzanine floor in my garage complete with scenery. If you have the space, get one and share it with your children.... though don't forget to let them have a turn every now and then! Jayde Deverson - Garage Mahal International.