This guy is a design genius with the artistic clout to make it happen. Seriously he does UIs for hardware and software. It's insane that this is free. It's going to be my main platform for making music. I was already in the process of moving off of EnergyXT (abandonware), but this skin makes Reaper like having a wonderful huge mixer to work with.
Okay, so why am I endlessly posting about skeumorphic interfaces when I am a noted objector to them? I object when the metaphor doesn't work well enough or when the implementation is harder to use than a simple UI using the platform-native widgets.
What you get here in this mixer skin is a number of what Don Norman calls affordances--the way a polished metal panel on a door affords (suggests) pushing. Here the controls are so very 'tactile' that the sliders afford sliding, the knobs, turning and the buttons being pushed.
Here the 3D element provides an excellent set of contrasts in the differing kinds of knobs, along with the physical beauty. The artist is fully conversant with traditional mixing boards and is using that set of controls and layout. It's not slavish, though, it takes advantage of things like tooltips and and pop-up menus. It's not a replica of any specific vintage console, but it speaks to my heart.