Little shared experience for those talking about the DIY balance board setups: if at some point people might step to it who don't have proper skateboarding experience (particularly in slamming), make sure you screw a type of stopper on the outermost two bolt holes either end (see how the Huka thing has it). If you don't and a kook loses their balance, the board will accelerate and shoot out over the tail or nose, becoming a missile, while the kook becomes horizontally airborne and bodyslams sideways onto the roller on the floor. Leading, in the particular instance I bore witness to, to a dislocated thumb incl ligament tear, a severely bruised hip and a slight concussion, plus a dent in the wall of a recently renovated rental flat. Cherry on the cake was the dude was about to be a dad and spent the first month of his kid's life not being able to hold it or properly support the mom.