Which leaves us with the throne - and the idea is out there already. Sonor offers a cajon with upholstery.
Overall the percussion sector is rather innovative and the day where you would find - on the off chance - just a single lost cowbell on a set, are long gone. World beats - but also grooves we are all familiar with from sequencers and drum computers demand a variety of instruments on the set.
Experiment and be playful. Just look at cymbal stacks, developed as signature models, in order to produce an artificial , and sometimes even a "broken" techno sound.
Metal plates, tins and tubes - and we are not talking chimes here - rather their raw colleagues and other "scrap" have found their way into many a set.