attaching barriers directly to chamber sidewalls typical frame 110 and thus panel 132 is received in an opening 134 of the sidewall 140 of chamber 120 as shown in fig1 in one embodiment the frame is mechanically snapped into place by virtue of the interlocking design of the edges of the opening and the periphery of the frame in another embodiment the frame may be bonded welded screwed or otherwise fastened to the chamber wall surface adjacent the opening or within the periphery of the opening in another embodiment the frame shape approximates the opening shape and the frame is attached to the exterior or interior surface of the chamber sidewall adjacent the opening in still another embodiment the frame 110 is captured in the sidewall by positioning it within an injection molding mold during the step of injection molding the chamber when separately fabricated panels are used the barrier is characterized as being indirectly attached to the sidewall of the chamber fig1 shows a further embodiment of the invention an assembly such as assembly 400 comprises a set of two or more panels 410 three are shown in fig1 spaced apart along support bar 412 the spacing corresponds with the spacing of openings in the chamber sidewall thus many panels can be set in place simultaneously in openings in the sidewalls bar 412 can be left in place after the panels are placed onto the sidewall or it may be cut.