Hello, random number is 7, file can't be uploaded here, but you can take it from [login to view URL]
Your project is multi-skill, I suggest web based solution (login requires Database, change password, pass recovery etc, membership status,), payment will require some gateway (Paypal ? ) for automatic confirmation, some admin panel for you will be required (to change prices, add new colors or similar), web app should work on mobile phones and tablets ... Calculations are basic, but there probably are some catches, example some sections types excludes - includes other possibilities (I am not fence expert), interactive interface is interesting challenge - solvable.
Please take a look at my profile and Completion Rate.