Hi Troels,
Here some pics on my Discovery 3 Way Classic -project. Thanks for design, they sound great and I'm very happy with result. 
My original thought was to upgrade CSM crossovers but when you published Discovery mkII decided to start new project. There is something special I like about in these Classic Designs.
Cabinet is made 19mm mdf and finished with teak veneer and lacquer. Front panel is spray painted, waxed and installed with M6 umbraco screws. Stands are based on Gah-Alberts XD corners and some 6 meters of 30x30 steel profile. 
Best Regards,
Timo

Here some more info and pics on stands. No special tools or welding needed in building. I used only bench drill.

XD corners are made of polyethene and are available on different forms and sizes. More commonly they are used to make work benches, tables etc. I found suitable parts from Amazon.de. Good thing is that you can make stands on exact size. Construction is also well damped. 

https://www.gah.de/en/products/profiles-sheets/assembly-accessories-for-profiles/

I used 30x30 mm steel profile with 1,5 mm wall thickness. Corners are designed for aluminium but 2 mm wall thickness is bit too tight. Aluminium is also more expensive and difficult to paint.

I was lucky to find place to purchase profiles cut on exact measures. Getting straight cuts by hand would be very difficult. There is anyhow quite much filing and sanding to be done.

The 40x5 mm steel plates for feet are attached with screws. For this I added wood plugs inside corner part where needed. Painting is done with foam roller before assembly.

Total material cost for pair was around 140 euros so I think it was worth of effort.