[PSUBS-MAILIST] STS SubDesigner shell / head calculator

[Jon Wallace via Personal_Submersibles]

Sean, great tool.  A couple of enhancement requests for the future.

1) Drop down list for material type instead of clicking through the list

2) Change between metric and imperial numbers without having to 
recalculate and enter numbers again

3) Allow manual entering of material properties for non-standard 
materials.  One example, I'd be interested in using this to calculate 
limits for PVC and ABS housings (lights, sensors, etc)