fully parametrical drag chain

as promised, here's my fully configurable drag-chain!

A) width, height, length are obviously changeable.
B) you can also change the maximum upper and lower bending angle
('0' means it's not possible to bend in that direction)
C) you as well can specify the connection axes: inside or outside
D) finally it can be chosen whether or not the top should be opened or closed
- just have a look at the provided OpenScad screenshots!

Remarks:
A) the print tolerance as well as the maximum allowed angle is specified not by a parameter but by a single variable at the top of the script
B) as the closed version is stable enough, the inner hole is rectangular;
the open version has an elliptic hole to add more stability to the inner corners...)

-- I'm closing this now; it already takes quite a long time to compile/render (while it still is rated 'simple' by OpenScad)
...plus: I really don't know what more to add... ;-)