Since the PICA plan does not have a parts call-out or take off, It won't be as easy as plans with the parts sheet to scale. If I were to blow the PICA to 1/4 or 1/3, I think I would trace all the parts, and have the plans blown, and get the parts tracings blown at the same time. Plan on spending some time here, since the parts are not identified, except on one page of the manual. Take your time and go piece by piece. clean up the die crunching on the parts (you don't want to transfer all the Fubars to the tracings). I've done this, and I think it's worth the effort. You will need to make allowances for things like spars and stringers, because when you blow from 1/5 th to 1//3 scale you are going from 1/4 X 1/4" stringers @ 20% to about 7/16 X 7/16" stringers, and these sizes are not readily available. Most of the time you can get by using the next size up, which will be 5/16" square or 3/8 square. Also the sheeting becomes a nightmare, because the length will require some serious splicing or you will have to buy odd size sheets. Don't let this intimidate you though. The WACO should be a great model in any of the larger scales. You will have to do your own thing on the ailerons to match the corrugations and such. I would consider finding an aluminum mixing bowl at Wally-World for the Cowl. You would be surprised what you can do with a 2 dollar hunk of aluminum from the housewares section.
Everything is going to be bigger. Even the silly Grin on your face after the first flight.
