Build an Online checkout and quoting system for 3D printing

I need a quote system to be developed for my website www.insta3dprinting.com. This is a wordpress site that is already being developed. You have to design a system as follows: 1) when the user clicks the upload button, you need to upload the file and validate that it is an STL file. 2) the maximum dimensions of the object contained in the file needs to be checked against the maximum dimensions provided by me. I will give you a readymade PHP script to get the maximum dimension and also to display the STL file. 3) the volume of the file needs to be determined. Again there is a readymade PHP script for this. 4) the user needs to input his choice of material, colour, etc. and other settings. Based on the volume and other input settings, the total material weight required will be calculated. I will provide the formula for this calculation. 5) the calculated weight needs to be checked against the weight of the specified material contained in a material database. this database will be deducted the weight of the object once the payment is confirmed. the database will be manually updated once a week based on physical stocks. 6) Once the fie is confirmed, then give the customer option to add more files to the cart using same process as above. 7) Checkout: after all files are added as per user requirement, get personal details and shipping choice. Output total amount to be paid and proceed to payment gateway, preferably payzippy. This system needs to be integrated into my wordpress website. As mentioned, readymade PHP scripts are available for all the calculation for STL files. Other open source and github hosted resources for manipulation of STL files is also available. HEnce you do not need to learn about the file format or write any code for it. Essentially, you have to code for a simple ecommerce website.