Ema Stack stackable gadgets system

A while ago I had an idea to create a system of stackable gadgets that may be useful in many occasions. The idea is to have a battery pack that will have USB charger in it and contacts on top that may power other device(s). These other devices will hold using magnets. Top of the device will have contacts and magnets so more devices may be added. Those devices may be lantern/lamp, Bluetooth speaker, clock/barometer/thermometer, etc. All electronics is based on cheap widely available boards. As se