By combining router bowl and resin board techniques, B2W has developed its latest genre: the river bowl! The process will likely evolve, but so far, here's what's involved.
Step 1: Create plywood molds coated with Tyvek tape to prevent the resin from adhering to the mold. Coat all the inner seams with caulk to prevent resin leakage.
Step 2: Create rectangular layered blanks of hardwood to fit inside the molds.
Step 3: Remove portions of the blanks that will be replaced with the resin "water."
Step 4: Secure the wood portions to the mold with screws to hold them in place and to prevent them from floating when the liquid resin is added. The screws are placed in the waste portion of the bowls, and the entry sites are caulked to prevent leakage of the resin. Small reinforcing struts are place between the main wood sections and are used to hold any "islands" down.
Step 5: Once the resin has cured, the bowls are hollowed out following a template and using a drill press with a large 2.5" Forstner bit.
Step 6: Usual finishing process of bandsawing the outer waste away, sanding, routering edges, oiling, and waxing.
Future refinements will likely involve innovations to limit the amount of resin that is wasted. Resin is expensive. Filling the upper layer of the river portion (that will be removed with the drill press during the hollowing out step) with wood is the current idea for future generations. We'll see how that goes...