The dressage arena out at the stable needed a little definition, so after studying the offerings in some catalogs, I figured I could make something that would pass as suitable and not be so costly. Materials I used are the square shaped plastic rain gutter downspouts I found at Home Depot for about $10 per 10ft length, and the uprights are made from 5"x5" plastic fence posts (about $25/8ft.) that I cut into pieces and then carved out some holes for the long pieces to fit into. Caps for the uprights I found on Ebay for about $1.50 each. They are glued on.
I made the corners first and then placed some others where the marker letters are positioned.
Total cost for the four corner areas was about $150.
I started this project over a year ago. They stood up great in the summer, but when the blustery weather came around they toppled over. Some wooden stakes and hay bale string solved that problem. This stuff isn't heavy so it is easy enough to stash it all in a barn when the weather is really bad.