Building your own fish tanks can not only save you money, but can also be a rewarding way to incorporate the tanks into your home. For the first tank, you should probably start small, learning the basics. Then you can build larger custom-shaped aquariums.
Draw the basic outline of the tank, including measurements. Try to be as exact as possible, so you can use the diagram to purchase material in the correct sizes.
Buy the acrylic pieces to make up the sides of the tank. Pre-cut pieces can be purchased at major home improvement shops, but the staff will not cut the pieces to exact sizes. Visit an acrylic shop for custom sizing.
Pick acrylic pieces thick enough to support the height of the tank. A thickness of 0.6 cm (1/4 inch) works for heights up to 30 cm (12 inches), 0.9 cm (3/8 inch) for up to 45 cm (18 inches), 1.25 cm (1/2 inch) for up to 60 cm (24 inches) and 1.9 cm (3/4 inches) thickness for up to 75 (30 inches) in height. Taller aquariums may need specially cut pieces, so you should speak with your supplier about the proper thicknesses you need to build your tank.
Cut the top and bottom panels about 0.6 cm (1/4 inch) thicker to allow for seaming. The side, front and back panel should all be the same height.
Router prep the side panels by cutting grooves into all four edges. The front and back panels should only be router prepped on the top and bottom.
Cut out any additional holes you will need from the top sheet. Draw guides on the protective sheets and use a jigsaw to cut out the pieces. For longer lines, you can follow a straight edge with your saw.
Line up your pieces and peel back the protective paper from the edges.
Leave a slight overlap on the joints, so the acrylic has a place to stick to as the solvent works.
Apply WeldOn to the seams (see Resources below). A syringe or plastic squeeze bottle will allow you to control the flow of the solvent better, which means cleaner lines. Be careful not to drip the WeldOn, as it begins to set very quickly.
Have a friend help you hold the pieces together while you seal the seams.
Avoid bubbles in the seams. The pieces you are joining must be even or bubbles will form. Practice sealing seams on scrap acrylic.
Seal each seam with the WeldOn and let them dry for 3 to 4 hours at the very least. For larger fish tanks, you should let each seam dry before adding the next piece.
Dry the sealed tank overnight.
Sand down any rough or sharp edges on the outside of the tank.
Let the tank cure for at least a week before adding water. The longer you wait to add water and fish, the better the seals will hold. Waiting up to a month is common.
Remove the protective paper from the acrylic and rinse before adding water.
Use scrap pieces of acrylic to practice sawing, routing and seaming. This lets you build your experience before you start working on actual fish tanks. Leave the protective sheets on the acrylic until you start seaming. This protects the pieces from scratches.