Rändrahn is my first attempt at a concrete bluetooth speaker. 

The shell is poured from concrete, as it creates a very dense and strong barrier for sound waves. The resulting sound coming from the speaker is impressively rich considering its size. The weight however puts it at a disadvantage compared to other bluetooth speakers. 

​

Its best feature is its battery. A 20000mah battery means that this bluetooth speaker has over 100h of playtime on one charge.