Hello,
We believe you are looking for an online store which will also have a designing tool which will allow the users to design their apparels by following few guidelines and selecting options from the tool. Will there be pre-loaded designs too? Which payment gateway do you need? We have worked using PayPal api and have developed few eCommerce sites. We have done almost all the features needed for an online store like delivery methods, payment integration, product page, slider home page, package tracking, invoice printing, multi-vendor functionality, etc. We can share the examples of the online store for a reference.
If you have any questions or need any clarification, please contact us. We look forward to your valued response.
Regards,
OKTeam