Event Reg form/process with QR code integration and badging

To develop a registration form, that can be easily updated (like Gravity Forms/WP Forms), that can take paypal/stripe payments, but email ticket confirmation with QR code integrated. Also produces invoice of attendee registration. Reg form will need to be flexible to take different types of registrations, that relate to different badge designs. Discount coupons also need to apply.
Develop App so when arrival at event, QR code can be scanned from ticket to confirm check-in, which produces bespoke badge with attendee info, and QR code on badge. Badge as a pdf for printing (A5 to a set design which also needs to be updateable).
Separate App for scanning badge QR code to display details of attendee.