Toman you can make your own template from your own Shen scroll like Ken says.
This is what I did to copy one.
Start with a line where the neck/fingerboard joint is and extend the line another 40cm past the nut. Mark the nut position. Use a ruler and setsquare to find the point on the line directly opposite the centre of the scroll button and measure that and transfer the point to the drawing. The rest of the profile can be drawn using a compass using the two points as reference.
For the volute, draw a cross centred on the scrollbutton and take lateral and depth measurements. Then joint the dots.
The advantage of doing this, I think, (apart from the low dollar factor) is that you learn a lot about the scroll as you decipher it for the drawing. I did. It's quite a complex 3d object. I haven't carved one yet, but I'll need to do it soon ...
To see how well you know double basses, try this challenge.
Don't look at your instrument. Take a clean sheet of paper. From memory, draw an F hole. Draw a scroll.
Much harder than you think!