Actually, I have a mixing console, even a quite good one, but sometimes you need something smaller that can be set up and taken down quickly. Especially when you have to deal with limited space. In my search, I chose the Versatile 4-Channel Mixer from Everyday Practical Electronics magazine 2009-04. Mainly because of the integrated loudspeaker and the individual input signal configuration.
For legal reasons, I cannot offer an excerpt from the magazine for download here. However, the magazine can be found several times on the internet; just google it.
I ordered the circuit board from England, directly from the magazine publisher. It does not have an assembly print, which made it a little more difficult to assemble. Also, all holes are drilled with 0.8 mm and you have to re-drill the holes yourself that need a larger diameter.
I also bought the original housing because it seemed the easiest. In the meantime, I would prefer a different enclosure. It is difficult to insert the glued-on front and rear panels into the slots provided without them sticking out and forming ugly corners.