How to Make Hard Resin-Based Plastic Aquarium Plants

Written by gary powl
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How to Make Hard Resin-Based Plastic Aquarium Plants
Embedding aquarium plants in resin bases keeps them in place. (aquarium image by FotoWorx from

Plastic plants decorate many aquariums. They create a realistic-looking, colourful environment for fish without the many requirements of sustaining live plants. However, all it takes to destroy the pleasing visual effects of live plants is one or two destructive fish in the tank, who can easily dig them up and send them floating. Stop this from happening by fabricating heavier resin bases for aquarium plants, which makes them more difficult for fish to move and prevents them from floating freely.

Skill level:

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Things you need

  • Polymer clay
  • Aquarium-safe polyester casting resin mix
  • Silicone rubber mould-making mix
  • Spray-on mould release
  • Plastic aquarium plants
  • Foam board
  • Poster board
  • Tape
  • Stir sticks
  • Hot glue gun with glue sticks
  • Talcum baby powder
  • Drill with small bits
  • Aquarium-safe silicone glue
  • Dish soap
  • Toothbrush
  • Latex gloves
  • Surgical mask

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  1. 1

    Sculpt the polymer clay into a base. Bake the clay according the instructions on the packaging.

  2. 2

    Glue the top of the clay sculpture to a square of foam board, leaving at least 1 1/2 inches of foam board all around the sculpture.

  3. 3

    Cut the poster board into a piece large enough to encircle the sculpture, leaving about an inch of empty space all around. Tape the poster board into a cylinder. Position the cylinder on the foam board with the base sculpture in the middle, then use hot glue to hold it in place. Make a solid bead of glue all around the base, then allow it to dry thoroughly.

  4. 4

    Spray the sculpture, foam board and poster board with mould release according to the instructions on the can.

  5. 5

    Place the sculpture and mould frame on a level surface. Put on the gloves. Thoroughly mix the silicone rubber according to the instructions. Pour the liquid rubber over the sculpture and continue to fill the cylinder until the rubber is about 1 inch deeper than the sculpture. Allow the rubber to harden until it is springy and dry to the touch, at least overnight.

  6. 6

    Tear off the poster board wall and peel the rubber mould off the foam board and the sculpture. Work your fingers around the base of the mould to help loosen it as necessary.

  1. 1

    Sprinkle baby powder into the mould and work it around inside until the entire surface has been powdered. Blow off the excess.

  2. 2

    Move to a well-ventilated area and place the mould on a level surface. Put on gloves and surgical mask. Mix the resin according to the manufacturer's instructions. Be precise in your measurements and stir the mixed resin thoroughly. Pour the resin into the mould and allow it to harden, at least 10 minutes.

  3. 3

    Remove the resin casting from the mould. Leave it alone for 24 hours.

  1. 1

    Thoroughly wash the resin casting with dish soap, scrubbing with a toothbrush. Then rinse it several times with tap water only to remove all traces of soap.

  2. 2

    Drill a hole in the top of the base, large enough to stick in the base of the plastic plant. Put silicone aquarium glue into the hole and stick in the plant. Allow this to dry.

  3. 3

    Rinse the base and plant again. Submerge them in a container of water and leave them there for several days. Remove them and check the base for signs of damage.

  4. 4

    If the base shows signs of cracking or breakage, discard it. If it does not, place the plant in your aquarium.

Tips and warnings

  • Molds are good for multiple resin castings.
  • Protect skin, eyes and lungs while mixing and drilling resin.
  • Castings that do not thoroughly harden are unusable. If there are signs of sticky resin "seepage" on the casting, discard it.
  • Resin generates heat while hardening.
  • Never place a resin casting in an aquarium until mould release and soaps are well rinsed off.

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