One of the chamber blocks fits in the main housing to create a small formicarium large enough to contain a young or small colony of ants. ~ A 1/8" thick piece of acrylic or clear plastic is needed to complete this piece. The dimensions are 1.633" X 2.212". If you only need one piece, visit www.byformica.com and Contact Us to inquire if plastic pieces are available. ~ Development for this project has been suspended, and the models will be deprecated by a forthcoming design.Hexagonal Chambers - Best suited for small ants, the depth of the hexagonal chambers may be customized by adding plaster. ~ 3-row Chambers - Works best for larger ants that can not fit through the vent openings. Chipboard or cardboard is cut to fit on the vents, so water may be wicked through. The user may also add plaster and dirt fillets to tailor the shape of the chambers. ~ 4-row Chambers - Experimental, winding design. Plaster or other barrier should be inserted into the back vents so ants can not crawl through. ~ 5-row Chambers - Experimental design for very small ants. ~ ~ Main Housing Notes -