Build a slow feeder? (for hay)

I have a very easy keeper. I mean this guy can get fat off of the air! Anyway, for a while I tied up his hay in a small hole hay net, but he still managed to waste a whole bunch. I moved him pretty recently, and since haven't incorporated the hay net again. I may try it again but I'm not sure. I'm not the one who feeds him all the time, so I don't know that the barn owner would be willing to shove hay in a hay net. Rambling here, sorry! I would like to build my own slow feeder. The type that is made of wood, has a lid, and a grate on the top that allows for the SLOOOOWWWW "grazing" way of eating. Now I have not the slightest idea of how to go about this!

Anybody have experience with building this type of stuff? And some instructions ;)

Subscribing! I'll be using one this winter for my mustang who is a PIG and an easy keeper, bahaha :P

I posted several ideas in this thread
making a slow feeder

Hmm.. I would try a different hay net. Who big is the holes? I would go down to a 1x1 hole if they are bigger than 1x1. You can also not fluff up the hay, just put in heavy flakes (that are really compacted). But, here are some good ideas:
http://paddockparadise.wetpaint.com/page/Slow+Feeders
You can get some heavy duty mesh, no climb mesh, that's the stiff stuff, fit a wooden/metal box to it, put it inside and walah! Horses figure out ways to make it easier to eat though.