To make things even cheaper like foam rocks you could go to your local habitat store and they had some 2.25" thick 4x8 pieces of foam that i bought for $5.00/sheet and you could have made your boulders from that.
Rather then go to lowes and buy a sheet of plastic for $100.00+ go to the habitat store and buy a used screen door with the plastic window insert for $10-$20.00 and use it. I did that for a guy who wanted see thru cabinet doors down low in his kitchen but didn't want to use glass because of his little kids.
I love shopping in the habitat store because i find things that can be used for some completely different repurposing.
And I agree with Doug that for a lot of us it's more about the creative journey and the things we learn by doing. I guess that's why it's called a "hobby".
Words of Wisdom:
“Words that sink into your ears are whispered…… not yelled”
“The biggest trouble maker you’ll probably ever have to deal with, watches you from the mirror every morn’n”
“The only difference between a rut and a grave is the depth”
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Just remember...when it's time for the hearse to pull up..there's no luggage rack on top!
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The beauty of the Second Amendment is that it will not be needed until they try to take it...Thomas Jefferson