What you see in these picture at left is the result. To highlight how cheap I really am, the 6-switch unit was made with the cover of a gas water heater I had to replace this past winter. I made a nice looking wooden base for it, but you can only see the wood base when you are holding the switch box. The wood does add a decent amount of mass to the assembly, though, which helps to hold it in place on the floor.
The 3-switch unit is a pretty simple and obvious device, except for the 3rd switch. As you can see from the schematic at right, the first two switches connect from ground/common to the ring or tip connector of the TRS jack. The third switch connects to both tip and ring through a pair of diodes (pay attention to the correct polarity) and to ground/common. It's not complicated wiring and the parts are cheap. I bought a pile (10) of cheap SPST momentary switches from Amazon and used them on both switch boxes. After almost a year of use, they are still working well. They are cheap plastic and I'm sure ham-footed use would break them and if you dawdle with the soldering iron you'll likely melt the plastic holding the solder tab. The switches must be momentary. If they aren't, you'll have to press the switch twice for each change action. That is NOT handy.
The six-switch unit is a little trickier than the three switch unit and requires some planning and assembly skills. Not many, though. Along with the six SPST momentary switches, you'll need another TRS jack and seven 10k ohm resistors (anything, wattage-wise, will work). You can see I staggered my switches, mostly because I did not want a long switch box and because my TC Helicon PerformVG only has four harmony combinations that I am likely to use, so the two offset switches are for voice echo and guitar echo, which I almost never use.
I've included a second drawing for the six-switch unit, in case that layout makes more sense to you. They look different, but they are exactly the same circuit. The drawing at right might more resemble the physical layout of your assembly, which might make error-free assembly easier. I should note that I did not create any of the drawings included in this blog. I snagged them off of the internet, like you probably did when you found this essay. I should go back and find my sources, but that was about a year ago and I'm lazy. So, I didn't draw them, I apologize for not giving full credit where credit is due, and I used them and they work. In fact, the 3-switch unit works incredibly well on my Roland Cube Bass, too.
