Top loading badge holders off Ebay from Japan are nearly the right length to fit in my pocket Malden. They were, however, not wide enough and I needed some way of adding holes for them to fit.
We found a sheet of clear acetate in our study and I cut a page size out.
I used Washi tape to secure the badge holder to the acetate and then punched some holes and rounded off the corners.
Cards fit perfectly and they can be zipped in if necessary.
I put 2 cards in each holder as both sides can be seen.
A perfect fit. Ten of these holders cost me £1.55.
My D.I.Y. card holders for a mini Filofax can be found here.