> DesdeChaves <mailto:desdechaves@gmail.com>
> 25. Mai 2016 um 19:09
> 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?
Is there a reason why you use \externalfigure because the width can be 
set with \scale, e.g.

     \scale[width=8cm]{\getbuffer[ammeter]}

Wolfgang