Abstract: A modular connector system for tubular structural members includes a variety of connector members, each having a connection wall for connection to a tubular structural member and a mating wall for connection to another connector member. The connection walls include cylindrical mounting collars and segments of cylinders. The mating walls include connector tabs and circular end walls. Each mating wall includes a peg disk relief, a fastener bore, and an array of peg recesses spaced about the bore. The connector members are secured together in sets of two, three, four, five or six by positioning a peg disk between the mating walls of the connector members to be connected together and passing a fastener through the connector members and the peg disk or disks. Each peg disk includes a peg disk plate having a fastener bore and an array of pegs spaced about the bore. The connector members are used to connect the tubular members to form various configurations of temporary shelter structures.