I need to build a new shed in my garden. Only a small affair, about 4x3 foot. It's going to stand on a concrete slab. Straight forward enough you may think. Now the interesting bit. It's to house a telescope so I need to be slide (roll) the shed out of the way to use the scope. We are in quite an exposed area and regularly get winds of up to 70mph. I need a way of easily(quickly) securing the shed to the floor. Can anyone suggest any ways of doing this. Is anyone aware of any off the shelf fittings that may work?