Thermostone from Apoolco - The perfect DIY pool system for self-builds: Thermostone is a self-produced system and Apoolco's own brand. It is the perfect DIY pool system for anyone who wants to build their own dream pool. The polystyrene pool system is perfectly harmonised and contains the right components for quick and easy DIY construction. With Thermostone, you can not only save money, but also build a premium product yourself.