For a basic multiples module, I used a led pencil to carefully mark the places where I will drill holes.
This is a mini jack to 1/4" jack multiples. Here I have also marked with a led pencil, the places where I will drill.
Be careful to make sure the holes you drill will fit whatever jacks you intend to insert.
Here we can see how the connectors are soldered together, not mixed. (An optional non-inverting, unity gain amplifier can be incorporated to prevent loading.)
I have been using paint markers to decorate the modules.
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Multiples

Multiples panels are relatively easy to DIY. A great 1st project for beginners!

Features:
- Mini Jack Interface Solution
- 1/4" TR Jack sends signal to multiple locations simultaneously.

Brian Tuley
Electronic Engineer Brentwood, CA