A paddle can be laborious to make. They can cost a lot to buy. Here's a better quicker way. The old-time Hawaiians sometimes made paddles this way. I've seen paddles made this way in Nicaragua. I've done a lot of paddling with paddles like this. They work great. Not much to it. Drill two pairs of holes in a board. Tie loops of string through the holes. Jam a stick in the loops and go paddling.
Here's a Naish carbon standup paddle that retails for $399. Next to it is my "copy" which didn't cost anything to make and took an hour or so of work. For reference, the blade is 9.5" wide and 18" long. The lashing holes in my blade are .372" diameter. The handle of the Naish is 1.15" diameter and is 86" long overall. If you want a T-handle on top of your paddle feel free to add one, the old-time Hawaiians never did.
In the surf industry this process is called R+D which stands for "ripoff and duplicate". The shapers all do it and joke about it with pride.
I traced the blade onto a piece of scrap paper. It happened to be a map of Burning man 2008. I folded the paper over to make sure my blade would be symmetrical and cut it out with scissors. I added a bulge at the top of the blade so the lashing wouldn't slide off.
My scanner is smaller than the paddle blade, so I folded the paper into quarters and scanned it as shown. I scribbled on the lower piece of paper so the edge of the paper on top would show clearly. The blade is 9.5" wide and 18" long. The lashing holes in my blade are .372" and are drilled in the fat quarter of the blade. Print this image out at the proper scale and trace it to make your blade.