Our current "ultimate" DIY-design so far has been the "Bendit" curved line array w/ 8 x 10" SB shallows per unit, 20 x Fountec and RAAL.
This is driven by 6 amps w/DSP. The Norwegian web-magazine made a review on them.
We have made many DIY-designs from small two-ways to common line sources, CBT, magnestatic, but none are comparable to the immense clear 3-d dynamics that Bendit can deliver.
The next design is "Moelva". This is a kind of Buchardt/D&D inspired curved line array with 12x 5" Satori Textreme, Satori BE tweeter in waveguide, 8 X 7.5" Wavecor subs at the rear baffle plus a Hypex 503 on the base plate. During this process we got some valuable advices from diy and pro collegues. The cabinet maker is also the owner. He is also making custom furniture, kitchen designs etc.