Draw the Rail

A build-it-yourself physics track. The ball has to reach the goal, and nothing between here and there exists until you put it there: planks, rails, springs, accelerators, bumpers, all dragged out of a panel and placed by hand. Press start and watch whether the thing you built does what you thought it would, which it usually does not the first time. There is no timer and no move limit, so Draw the Rail is less a puzzle than a workbench with a pass mark at the end of it.