Hi David, it happens already in figure 6! By writing path left; ... path right; you have redefined internal things "left" and "right". With e. g. %draw spring block left path xleft; xleft:=(2,9)--(3,9)--(3,11)--(2,11)--cycle; xleft:=xleft scaled u; stripe_path_a(withcolor black)(draw) xleft withcolor white; draw (3u,9u)--(3u,11u); %draw spring block right path xright; xright:=(17,9)--(18,9)--(18,11)--(17,11)--cycle; xright:=xright scaled u; stripe_path_a(withcolor black)(draw) xright withcolor white; draw (17u,9u)--(17u,11u); it works. Regards, Hartmut ------------------------------------------------------------------------ Hartmut Henkel, Oftersheim, Germany ------------------------------------------------------------------------