Sasha, those are AWESOME!
In order to have WETA make something, they'd unfortunately not look too close to the films' feet. Like Sasha said, you'd beat the CRAP out of those, just walking around a con floor.
The only time the actors had the feet on, was for up close shots and shots they knew would show feet. There were a ton of scenes where the actors had regular shoes on to get around. The latex would just rip too easily. You'd definitely have to make them over a shoe, or just make flesh colored flip flops and hair-up your own feet, which I've done in the past when I used to costume as Pippin!