I have built a number of audio devices in wood boxes. The timber box above is a Twinnings presentation Tea Box. This two stage valve preamp with remote PS performs beautifully partly due to the fact it is chock full of Cardas Golden Ratio caps and pure silver wire (see article below for more info.). In fact it performed so well, that on hearing it, a friend bought it on the spot. I had only had it a week. A switch mode 260V has PS has its own die-cast Al case. The lid was polished then clear coated. The base is black epoxy paint-quite attractive when paired with the Tea Box amp.
Though standard 12AX7(s) were used the preamp produced a very clean and natural tone across all music types. Classical music had a particularly enchanting and romantic feel from this preamp. When matched with a SS power amp, the full warmth and charm of valve pre-amplification could be enjoyed for many hours with boredom or fatigue. Distortion is usually an issues with valve gear but the levels for this preamp remain under 0.2%. It has a frequency extension to 180KHz! Great looking and great sounding.