Keeping slugs off mushroom logs

I don't know about you, but I've had it with slugs chewing on my mushrooms, so I've been working on various ways to create 'slug barriers' to keep them off my logs. Not wanting to use commercial slug bait or beer traps, I settled on working with copper.

My first creation was to build a crib of sorts. It's a pretty simple design, all you need are 4 logs (preferably debarked) and some copper pipe. I had some scrap 3/4" pipe on hand, so I went with that.

-  The logs should be about 48" long and 4-6" diameter.
-  Drill two holes in each log (matching the pipe diameter), about 30" apart.  **NOTE: do not drill all the way through the logs, 2-3" deep should be adequate**.
-  Insert 8" lengths of copper pipe into the holes on two of the logs (this needs to be a snug fit, I used a rubber mallet to drive them home). These will be your base logs.  
-  Then bridge the first two logs with the second set and hammer them home.
-  Stack your mushroom logs on top and you're done!

If you find the base logs wanting to roll over on you, drive a couple of lengths of rebar through the base logs approx 12-18" into the ground in order to stabllize them.

This setup worked out pretty well for me. After using this system for a year, I only found one or two slugs made their way to the mushrooms. After looking it over, I figure they crawled up a nearby twig to the stacked logs, so it's a good idea to keep the area free of any nearby brush or tall grass.