Don,
First a warning: POVRAY is not a CAD program and is not compatible with CAD programs. It is programmed in a unique language called scene description language and does not use a graphical drawing interface. The learning curve is about as steep as the side of Mt. Everest. I have been programming since 1963 so I don't mind. It is freeware with a ton of resources available.
The address is
http://www.povray.org
To give some idea of how it is programmed here is my code to draw the ruler. Once I have this written it is trivial to place the ruler anywhere I want, any size and any color. But programming it in the first place takes some time.
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#declare ruler=union {
box {<0,0,0>, <-36,1.1,-.1>
pigment {Gray}
finish {
ambient 0.8
diffuse 0.2
brilliance .5
reflection 0.01
phong 0.2
phong_size 1200
}
translate <5,6,0>
}
#declare i=1;
#declare j=.1;
#while (i<36)
box {<0,0,.001>,<.03,.5,.003>
pigment { Black }
translate <5-36+i,6,0>}
#while (j<1)
box {<0,0,.001>,<.03,.25,.003>
pigment { Black }
translate <5-36+i+j-1,6,0>}
#declare j=j+.1;
#end
#declare j=.1;
#declare numb=
text {
ttf "timrom.ttf" str(i,1,0) .003, 0
pigment { Black } }
object {numb
scale <.3,.4,1>
translate <5-36+i-0.05,6.7,.001>
}
#declare i=i+1;
#end
}