Take one piece of plexiglass and remove any plastic coverings.  Stick adhesive weatherstripping 3/4" from the edge of the plexiglass on three sides.  Attach another strip of weatherstripping on top of the original so that it is now twice as thick.  Remove the plastic coverings from the second piece of plexiglass.  Attach the second piece of plexiglass to the original, so now you have a weatherstripping sandwich that will contain the sand for the ants.  Around the three sides of the ant farm that has weatherstripping, caulk it flush with to edges of the plexiglass.  Let it sit overnight.  Carefully sift the sand between the two plexiglass sides until it is approximately 3/4 of the way filled.  Do not pack the sand.  Use clay to create a sturdy base.  Add about 30 ants through the top of the ant farm.  Place one damp cotton ball in the ant farm.  The cotton ball needs to be changed every other day depending on your climate.  The food that you add will depend on the ants you collect.  Add food to the ant farm.  When everything is finished, use clay to seal the top of the ant farm.