Although my backyard course was coming along nicely I wanted a really big and steep climb of some sort. I was turned on to this thread by a local TXRCRCA guy: RCC THREAD
After a few failed experiments I went ahead and began construction on Mt. Yamada. The basic idea isto make a frame of some sort and cover it with burlap, grout & mortar. I tossed around the idea of wood frames, chicken wire and even started on a wooden base for something but it didn't torn out well. One day while I was in Walmart I walked by an archery target and a lightbulb went off in my head. After construction a friend pointed out you can usually find free styrofoam on craigslist ... live and learn I guess.
PARTS & SUPPLIES NEEDED
3 Archery targets
4 x 1/4" x 12" dowels (plastic hanges work too)
4-6 yards of burlap
12.5 lbs of mortar
12.5 lbs or sanded grout
3 cans of great stuff expanding foam
4-5 cans of Duplicolor bedliner (AutoZone)
4 cans of paint
Dropcloth
5 gallon bucket
TOOLS
Sawzall with loooong blades
Electric carving knife
1. I started by unwrapping the archery targets and notching them to fit together. The sawzall cuts a lot faster and deeper, but also makes 10 times the mess.
2. Once they fit together, I used the dowels to "pin" the pieces together while using the Great Stuff as a bonding agent. Normal adhesive (and paint) eats the blown foam (archery targets) so I really suggest using the Great Stuff as a glue.
3. Once the main pieces were glued together I went ahead and started shaping the rock. I used some of the cut off pieces to add to the base to help with the climbing.
4. Up next I did some testing with paint. I found that putting on a very light coat of low solvent primer was OK, but if the primer built up at all and got wet it would eat into the foam. Then, because I'm impatient, I went ahead and hit the whole thing with primer just to see what it would look like.
5. At this point I did a little testing and found the rock was going to be quite difficult to climb. Using what I had learned about the paint melting the foam I "burned in" some channels that are my track width to lessen the angles.
6. Once it all dried and was shaped the way I wanted, I started with the grout/mortar mixture. I used a 50/50 ratio of mix (about 5 lbs of each) and added water until it was pancake batter consistency. Next I cut some strips out of the burlap and after soaking them in the mix I layed them on the foam. I tried to make surte the strip was well covered with mix but not excessivly. I started on top and worked my way around to the sides and was pleasantly surprised at how well it stuck to everything. While the top part was drying I did the inside & underside of the tunnel, then worked back out and got a second layer on the top since it will see the most abuse.
7. After that had dried for about 24 hours, I decided to paint the grout with bedliner to help hold it together and seal it. The bedliner then got painted with a few different colors of paint (I'm still workingon a good color).
8. Overall I'm very pleased. The top is 35" and it only weighs 56lbs. It seems to be holding up to my abuse with the exception of one part where I used some pool noodle (which I purposely left out of the writeup). if I do hurt it it will be easy to touch up with bedliner and paint too.
Here is a little video of me going up in the garage:
