ONCE YOU HAVE CUT THE 2 PIECES FROM THE PLYWOOD, YOU’LL HAVE 2 SHEETS WHICH LOOK LIKE THIS (9 FOOT HIGH HALFPIPE):

DID YOU LIKE CUTTING THOSE OUT? GOOD! ONLY 10 MORE PAIRS TO GO!

BUT FIRST, THE NEXT THING TO DO IS NOTCH IT OUT FOR THE RIBBED SUPPORTS (2 BY 4’S) TO FIT IN. THIS IS ONE OF THE WORST PARTS OF THE WHOLE PROJECT, AND KINDA DANGEROUS IF DONE ON A TABLE SAW.
 
 

EACH OTHER . THE 1/2" PLYWOOD WILL BE SCREWED ONTO THE 2 BY 4 SUPPORTS,  AND THOSE SUPPORTS WILL FIT IN THESE NOTCHES..GET IT? ....DO NOT NOTCH ENTIRE FRAME, AND DO NOT CUT  OUT ALL THE FRAME TEMPLATES WITHOUT FULLY COMPLETING THE FIRST  SECTION **..REASON? IF YOU MAKE A MISTAKE ON THE FIRST ONE, YOU ARE  LIABLE TO REPEAT IT ON EVERY SUCCESSIVE SECTION, AND YOU MAY NOT KNOW  IT UNTIL YOU START PUTTING IT TOGETHER..WHICH IS TOO LATE...

**A "SECTION" CONSISTS OF 4 FRAME PIECES CONNECTED TOGETHER TO FORM ONE QUARTERPIPE, AND THERE ARE 6 SECTIONS IN A 12 FOOT WIDE HALFPIPE: