Linking "Custom" size variant to another page where users can enter measurements

New Member
1 0 0

Hi all,

We are making a clothing store where we want to give the user the option to enter their own measurements. 

How do I link a size variant named 'custom' to another page on the site where people can enter their measurements? Exactly like how it is done on this page: 

I've been looking at forums and shopify apps but I've found nothing that fulfills this need. 

Here's the link to a product on my website:

Password: waheguru10

Any help would be great!

Thank you in advance.