In our area Clementines come in nice little wooden crates. I have a bunch, which I have turned upside down on the computer monitor and the TV. Because they are small, they fit that ridge, so I can use it for storage.
One of the electronics firms here in town regularly gets rid of wooden crates. I went to the shipping and receiving boss and asked if I could have them. They said "sure" as they used a lot of man hours breaking them up to go to the dump.
I have used these for a small garden shed, I have torn them apart for the wood to make standup Christmas ornaments for the yard and best of all my local animal rescue loved these for dog houses for the bigger dogs.
Look around and call your local moving and storage or an assembly plant. You to could be rolling in free plywood, too.
By Debra in Colorado