v0.6 - Mechanics

Very minor mechanics change from v0.5 - the spool strut tab is now "stepped" so that the distance between the spool walls doesn't depend on the exact thickness of material used. This should avoid issues with flaps binding against the walls of the spool if the material thickness is below spec (e.g. when ordering from Elecrow which seems to be ~2.8mm thickness rather than 3mm). See animation:

Also, based on feedback from someone who ordered recently, I'm generating a separate Acrylic laser-cutting file with a smaller kerf correction value than Ponoko specifies to hopefully avoid slightly oversized parts that require sanding/filing to fit together.