I used a mix of West system 105 and G-flex, and cabosil to thicken on one Sugar Island paddle 3/16" past paddle edge, built up another tip with a higher proportion of g-flex in the mix and greater volume on a modified otter tail, polyester cord and g-flex on another Sugar Island, another solid cherry otter tail has a maple spline at the tip and has held up well over 25 years. Both Sugar Island paddles edges grooved to provide key for epoxy and covered with 2 oz cloth, otter tails simply coated with several coats of oil/solvent/varnish. Next time I cover blades with cloth and integrate tip guards I will make the blades considerably thinner for better balance.
Basswood is great material for prototypes, light and very easy to work. would seal end grain with clear epoxy mix before casting with coloured mix next time.
Would be curious to try phenolic sheet - argument for this would be less fuss with forming epoxy? Softer? I thought that West System 105 on its own would be too brittle, adding the g-flex definitely softened the end result.