For educational purposes I try to simulate a ammeter for reading practice. I would like create six or more ammeter with different readings, but i'm not able to do that because metapost create the same random number every time I call the buffer that defines my ammeter. How can I fix that? Thanks Jorge My code: \startbuffer[ammeter] \startMPcode r := 4cm; len := 10bp; min_thickness := 1.75bp; hour_thickness := 3bp; path cadran; cadran = fullcircle scaled (2r); numeric escala; escala := 0; for i = 50 upto 70: if i mod 5 = 0: j := i div 5; angl := 90-30j; freelabel("\tfb\bf" & decimal escala, (r+len)*dir angl, r*dir angl); draw ((r, 0) -- (r - len, 0)) rotated angl withpen pencircle scaled min_thickness; escala:= escala + 0.5; else: angl := 90 - 6i; draw ((r, 0) -- (r - .5len, 0)) rotated angl; fi endfor pickup pencircle scaled min_thickness; numeric minute; %randomseed := uniformdeviate infinity; minute:= 50 + uniformdeviate(20); pair A, B, C; A:=1.6r*right+.5r*up; C:=1.6r*right+.8r*up; B:=1.1r*left; drawarrow origin -- r*dir(90-minute*6) cutends (0, 1.5len); fill fullcircle scaled .75len; draw unitsquare xscaled 3.2r yscaled 1.5r shifted B; label("\tfb I (A)", 1.2r*up+1.6r*right) withcolor red; draw fullcircle scaled 2len shifted A; draw fullcircle scaled 2len shifted C; \stopMPcode \stopbuffer \startbuffer[programa] \placefigure[center,nonumber]{}{ \startcombination[2*1] {\externalfigure[ammeter][type=buffer,width=8cm]}{\_\_\_\_\_\_\_\_\_\_$\pm$\_\_\_\_\_\_\_\_} {\externalfigure[ammeter][type=buffer,width=8cm]}{\_\_\_\_\_\_\_\_\_\_$\pm$\_\_\_\_\_\_\_\_} } \stopcombination \stopbuffer \starttext \dorecurse{3} {\getbuffer[programa]} \stoptext