(Edited for intent) For anyone reading this thread who’s interested in DIYing something like this by hand, here’s a basic overview of the process. Maybe it’ll help tip your descision one way or the other.
As far as attaching cheeks or similar projects go, if you have some experience with woodworking (particularly, knowing how to SAFELY use a router and a band or jig saw) and access to a router/accessories, a bandsaw or a jigsaw, the basic process is within reach of an intermediate hobbyist.
In short, you trace out the contours of the mixer profile on a large sheet of paper, then transfer that to a piece of MDF, 1/4” plywood, acrylic sheet (my preference) or phenolic. For some projects, you can skip the paper step and place the template material against the side of the mixer and follow the mixer contour with a pencil or scribe tool directly on the template material. Use a bandsaw or jigsaw (depending on the size of the panels and the size of your bandsaw table) to cut the material along the transferred lines. No need to worry about channel width or bit depth at this point. This just becomes your router template.
Tape the template onto your side panel material using double sided tape. Use a router with the appropriately sized bit(s) (bit(s) would be the width of the channel required to attach the side panel to the mixer) and a roller guide to follow the template to rout the shape of the console profile into the side panel. If you have varying areas of relief on the mixer sides, adjust the bit depth and go back and deepen those areas of the channel to the depth needed. Assembly is then as Rob describes above.
this is the rough process. There are important details of course, but it gives you an idea of the level of effort and skills needed.
Tip: when routing the channel, either use a compression bit or spiral downcut bit to eliminate chipping the wood around the channel. Alternatively, put masking tape over the area to be routed out.
There are probably many videos on Youtube that show the process of creating a routing template for similar applications. Do a Youtube search for something like, “making and using a router template”, and there are probably many instructional videos. If you have some woodworking skills and access to the tools and you have the desire to take those skills up a level, this sort of project would be a good challenge. And the skills will come in handy for many other projects.