I would say it is a very easy project. I bought an 1 1/2" foam sheet from the insulation section and took off the skins (the plastic and metal sheets stuck to it) to expose the raw eps. Then I cut it using my electric carving knife. I glued it together with pl premium construction adhesive and used 2 1/2" screws to hold it together while the glue cured. You can kinda see in the pic that I have blocking - I threw those in to keep the foam from bowing. I'd probably add them in every 16" like framing. I placed mine lower than the top edge so that dirt will hide them. While that dried I applied self adhesive fiber mesh tape to the outside. Wrapping it from one side to the other slightly overlapping the seams as I went. It doesn't stick that well so I used spray adhesive to fix that. Once that was done I coated it with some surface bonding concrete mixed with an acrylic fortifier. If you're near a building supply foam coat or polybond is made to cover foam but I didn't feel like driving the extra five minutes to the supply house so I made my own foam coat. That's it. You can paint it or add another decorative layer but it's really straight forward and dries stout.
Thanks for the info! I think I see another weekend project coming up soon.