So I have recently tried stropping a knife using cardboard instead of leather. I worked on my RAT-1. The knife sees some mild to medium duty use and the factory edge has been long gone and resharpened since.
Oh my! I've never had a proper leather strop (always used a belt or piece of hide without adding any compounds, so not a fair comparison, probably), but plain cardboard does a fantastic job. I set the edge first on my diamond-coated stone, then on ceramic and then I refined it on cardboard. Now I have knife-mange on my arms from shaving off hairs.
I took a shotgunn shell and sliced off the outer husk, kind of in the same way you'd wittle the end of a stick, and it went through it like hot butter. I wanted to check out the particulars of the shot pellets...
Tonight I'm going to do some work on my TAK-1. 1095 steel on that knife takes a little more time, but it mostly needs ceramic and then cardboard action. I plan on going backpacking this coming weekend and my main camp knife (the TAK-1) needs to be ready.
'16 Ecoboost F150
'12 Suzuki V-Strom 650
'17 Trek Fuel EX8 27.5+
'08 Giant Trance 1 (old school 26'er)