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Dear Bob,

Are you sure the 3D-printing is really necessary?

I think a much simpler and cheaper way exists.

Consider a backplane to which a pair of spacers are glued, a movable spacer for the slider's scale and the three scales glued to the relevant spacers. The key idea is to arrange the stator's scales to be wider than the movable spacer so that they (the static scales) overhang that spacer preventing its' falling out.

The (rather simplistic) sketch is attached.

All this make it possible to rely on laser engravement of the scales - I'm sure a much more precise process. The wide enought gap between the spacers - provided that the scales themselves are tightly pressed together by their edges - make glueing everything easier, just make sure the scales' indexes are aligned properly. One does not need to worry about the parallelism of the spacers, etc.

Two-layer white-cover/black-substrate plastics exist of wide list of vendors.

So an inexpensive DIY kit of the three scales and a backplane (with usage instructions engaved) is quite possible.

Regards,

Tony

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