To begin 3D printing the direct plant infusion or DPI device and mold components, apply a thin layer of polyvinyl acetate-based glue on the print bed of the printer. Load nylon filament into the printer and prepare the printer per the manufacturer's instructions. After importing the desired STL files, set up the printer and start printing.
Once the piece is removed from the print bed after printing, rinse the polyvinyl acetate-based glue from the base of the printed component with water. Spray the printed DPI device and other components with two coats of clear gloss spray paint. To fabricate the plastisol ring mold, assemble a mold form by building a rectangular enclosure using snap-together plastic blocks on a base.
It should be large enough to hold the pattern pieces. Mix the room temperature vulcanizing silicone or RTV silicone monomer and the catalyst together at a 10:1 ratio by stirring for one minute. Color the solution by adding three drops of food coloring and one milliliter of hand soap per 25 milliliters of silicone mixture.
Then, pour a thin layer of the silicone solution into the mold form sufficiently to fully cover the bottom of the mold form. Tamp to flatten the surface of the poured silicone, and wait for 24 hours to set the silicone. Once the silicone is set, pour another layer of silicone deep enough to cover the center hole core print of the pattern.
Insert the pattern into the liquid silicone with the center hole core print facing down. Ensure that no bubbles are trapped and the patterns are well separated and not touching each other. Secure the patterns with either a heavy object or tape to prevent them from floating out of the silicone while it sets.
Once set, pour additional layers of silicone into the mold form until the level is flush with the top of the pattern. Let the silicone cure for 24 hours. Disassemble the snap-together plastic blocks to release the mold.
Then, remove the patterns from the mold and inspect the mold for tears or deformities. For casting the plastisol rings, coat the interior of the mold, all the core components, and the O-rings with cooking oil. Place an O-ring around the notch in the middle of the center post core, and place the core in the center hole of the plastisol ring mold.
Insert the delivery channel core into the space on the side of the plastisol ring mold. Orient the V-shaped tip at the end of the delivery channel core to align with the O-ring on the center post core. Next, heat plastisol in the microwave for short bursts of 10 seconds till the solution reaches 160 to 170 degrees Celsius.
In between, stir the plastisol gently to avoid bubbles. Pour the molten plastisol into the plastisol ring mold near the outside edge of the mold without introducing bubbles. Wait one hour for the plastisol rings to cool.
Then, remove the rings from the mold. The DPI device was eight centimeters in height and three centimeters in width. It had a single central reservoir contiguous with the spout.
The total volume that can be contained within these components is 2.0 milliliters. The 1.8 centimeter tall and 2.7 centimeter wide plastisol ring also contained two channels. One to accommodate the DPI device spout and another of variable diameter for fitting around the trunk of the tree.
When assembled properly, the plastisol ring should be flush against the DPI device and the spout should line up with the hole drilled in the tree.
