Resin aquarium decorations are a great way to add some personality and flair to your tank. They can also be used to create hiding places and obstacles for your fish to swim around. Here is a simple guide on how to make resin aquarium decorations: Choose the design you want to make. This could be anything from a simple ornament to a more complex sculpture. Draw or print out the design onto paper. Cut out the design, making sure that all the pieces fit together properly. Tape the design together so that it forms one solid piece. Mix up some resin according to the instructions on the packaging. Pour the resin into a container that is big enough for your decoration. Carefully lower your taped-together design into the resin, making sure that it is fully submerged.