Bearded dragons will need at least a 40gal breeder type tank or larger. They can only be kept together if you have females and one male. Beards also love to climb so several branches and/or vines are needed. Having flat stones for rocky outcroppings and ledges is their favorite type of cage accessory. The only thing needed is added security by using wire to keep them secure. You could also drill holes in the rock (make sure you cool with water while drilling) and bolting them together. Make sure the rocks made so you can get the beardie out from under them again should they decide to hide, wedge, expand, and stick.