One day I was browsing reichelt.de and saw a small    
speaker on sale. A thought stuck me. Why not build a small portable speaker without    
bluetooth using cheap components? I quickly put together a list    
of design goals for my project:

• cheap speaker as audio source
• cheap powerbank as powersupply 
• cheap audio amplifier as... amplifier
• unergonomic case with sharp edges and corners
• loud obnoxious clicking sound (always on)
• clicking frequency adjustable by two RC circuits hot-glued on top of the case
• hot-glue massacre inside™

    
Needless to say it met all of the design goals mentioned above.    
    
10/10 would build again.