Welding generally involves using heat to create a bond between two or more materials. Although you can weld acrylic plastic with a hot air gun, acrylic bonding adhesives are an easier option. They create a similar bond and require no heat. These adhesives break down the molecular structure of the acrylic and cause the plastic molecules to bond, creating a welded joint that is as strong or stronger than a joint welded made by speed-tip welding the acrylic with a hot air gun.
Clean the surfaces of the acrylic sheets you intend to weld. Make sure there's no dust, oil, or other contaminants on the plastic sheets.
Place the tip of the syringe into the acrylic bonding agent, pull the plunger toward you to fill the body of the syringe with the bonding agent, and set the filled syringe aside.
Place one piece of acrylic plastic flat against a straight wall and place another acrylic sheet perpendicular to the first sheet, with the end of the second sheet pressed against the end of the first sheet.
Lay the tip of the filled syringe at the top of the corner where the two acrylic pieces meet and depress the plunger of the syringe as you drag the syringe along the seam to dispense the bonding agent into the seam. If your acrylic plastic sheet is thicker than 1/4 of an inch, you'll need to perform the step again on the other side of the seam to allow the bonding agent to penetrate the seam thoroughly.
Allow five to 10 seconds for the bonding agent to soften the surfaces of the acrylic sheet, then press the two sheets tightly together and hold for 10 to 15 seconds.
Perform the same steps for each seam you need to weld.
Allow the chemically welded seams to cure for 48 hours before you use the bonded acrylic sheets.