Do you build anything for your high fidelity system? If so, what do you make?

Gosh folks, I wound up building it all.  Power amps, preamp, DAC, active crossover, four way speaks (I need 8 amplifiers of varying power sizes), line array of 9 tweeters  and line array 5 upper mids, single low mid, two sets of  baffled woofers of 4 driver each.  It has evolved a lot of the last 4 years.

I built a 26"h x 78"w diffuser panel. It's actually an open frame made from 1x4 Douglas Fir with about 3,000 free floating pine, oak, fir and walnut angle cut pegs resting on each other.

@asvjerry  It's a linear tracker, which I tried to build without compromising rigidity or adjustability. That means expensive off-the-shelf stuff from Igus (costs more to make equivalent quality, IMO), three indexed linear slides and two slides with brakes on the sleds. Lots of machining too. I prefer Panzerholz to natural wood because it's rigid and has great damping properties. Lots of decisions peculiar to the layout - like where to hang wires and air hoses, etc.

Just installed this weekend, so still finding things that don't quite work together - luckily, little things. But the concept is proved - it's the most adjustable arm I've ever heard of, like tangentiality to the nearest 5 microns - the length of a medium large bacterium. Clarity improved from bass to treble, soundstage wall to wall and rock solid, speakers disappearing. That's over the former unit, also an air linear tracker.

I built my 4-way speakers. Built the phono preamp. Built the amps. Built the shelves. Built the turntable stand. Built the speaker cables and interconnects. 
 

Working on my first turntable. Built several styli for several of my cartridges. 
 

No plans to build a DAC.

Power cables, wall outlets, cable lifters, dc filter, modified my preamp and recapped my tuner.