Here is my design for a `1 IN - 4 OUT' selector, hand-operated. The orange selector part clicks between 4 prongs with rounded tops (from those knobs on the bottom of the ships, jet-skis, etc.) to engage the right gears. The spring in the central red axle I took from a small shock-absorber (it comes apart fairly easily, without really destroying it).
As usual, different colors indicate different subassemblies. I haven't drawn all parts, the 4-fold symmetry should make construction straightforward.
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