Here's how I did mine with 1/16 ply. 1 decide diameter, 2 set float size, 3 draw on ply (hint; 9 paddles are set at 40 degrees) 4 cut out (which does take some time) 5 mount meccano wheel on meccano shaft 6 glue all together and paint. Simple, cheap. crude but moderately effective and does not look too gross on the water.