[SML] riser platforms

[Dougherty, Jim]

Me four for Stagerights; ours are going strong with regular rearrangement
after 20+ years.  They do custom heights, too, if you¹d like.

They do have pinch points, though - just not the same ones as Wengers.
Once you know them, you can avoid them.
- watch your hands where the support frames enter the holes in the lids
- the support frames fold in a Z pattern, so no matter how you hold them
one arm can swing and hit your fingers.  We use velcro wraps to keep them
closed.

We¹ve also shop-built stress skin platforms to integrate with the system
so that we can use the riser supports for scenery, and avoid screwing into
the audience platform decks.

- Jim Dougherty
ATD, Middlebury College Theatre Dept.