Mats, like the retail mat, Nook Homes mat, T&T mat can not be made with custom designs. Basically for the T&T mat and the museum mat, it's either old store versions or the fossil/fish/art/bugs mats.
Ah ok, hopefully this will change in future versions. I was really hoping to be able to customize the flooring but oh well. Thank you both for the reply!
I’ll try to see what I can do with the scatter pappers. Though I was looking for something maybe less messy.