3d Print Cost Calculator

Very basic Java program I made a while back to calculate the cost of a print given the cost and weight of a spool.
Doesn't require install (if you have Java) and should work across systems.

Update: Android app is out!
https://play.google.com/store/apps/details?id=com.nz.ian.PrintCostCalculator
or
https://play.google.com/store/apps/details?id=com.nz.ian.PrintCostCalculatorPaid if you don't want ads.

Input:
Filament Type (PLA, ABS)
Weight of Spool (kg)
Cost of Spool ($)
Length of print (mm)
Output:
Length of Spool (mm (m))
Cost per metre ($)
Cost of Print ($)
Let me know if you find any bugs. Feel Free to ask questions.
Excuse the GUI design, haven't used Swing much.
NOTE: The stl is just a conversion of an image to stl so I could upload the calculator, not really worth downloading unless you are curious. Also while I have done my best to ensure the accuracy I can't guarantee it as the density of the plastics does vary, again let me know if you find