... 'Sidemount Schmiede' place, ...
If you have to bring his name into a discussion...
Yes, that's him. One of the best I met training at rec level and rec rates.
When I first met him he was diving a Transpac and I saw him in several other systems later, Kamaleont, Diamond, you name it.
Most of those he used for a long time, more or less 'destroyed' all of them.
He even dove with my second Razor for a few weeks when I did not dare to use it because of a damaged (and badly repaired overnight) wing.
To him all the commercial systems weren't adequate, even my beloved Razor.
He is more of an individualist than me and much more self sufficient.
He was one of those that already tried to have their own basic education using sidemount and where laughed at then.
Now, If you want to do that, just go to him, he is teaching nowadays and could be an instructor for any agency he chooses and is for some.
He isn't cheap either, but he normally works at rec instructor rates.
Technically that would not be legal but saves a lot of money.
'Technically' it is completely 'legal'.
He does not sell anything (or only some of the rare parts). His system is a rough concept he dives himself, not a product and two will rarely look alike.
He just recommends ways to others to build their own sidemount systems from scratch.
Several others did something similar here on scubaboard, other forums, blogs or facebook.
I personally have some moral issues with that, but friendship always requires some tolerance and I cannot force others to buy what I would.
Especially not people with their own experience of a few dozen or hundred sidemount dives, I give recommendations, often with drastic warnings and examples where required, then I help them with implementing or testing their own ideas.
When someone tells me he wants to do trimix dives in just a harness without a wing I tell him why he shouldn't and why I would myself die trying.
That is often sufficient to make them think twice and that seems enough most of the time to make rather competent decisions, from what I am observing.
Build your own systems will probably be seen even more often as people progress.
This area of Germany is full of dive shops but most struggle to sell any jacket for more than 250 or sometimes 350 Euros.
Tec divers have a lot of expensive equipment, but here many get most of it from ebay cheap.
Having tanks checked and certified is frowned upon by many tec divers here because it costs a few euros ever few years and they fill themselves anyway.
Rec divers here will problably never dive Razor systems at a rate of more then 1:1000.
In my opinion all the other systems are not significantly cheaper, to really save money you have to build your own.