Cutting shapes from domed plastic

[renaissance_man]

I want to cut a cog shape from some acrylic plastic that is domed.

I printed the cog onto papter and cut it out, but when it comes to then tracing the shape on the dome the curvature of the dome gives inaccurate spacing between the cog teeth.

Can someone help me out with a way to overcome this?
Here's a picture of the dome I'm working on.

Thanks
Jamie

 

[Sidewinder]

Cut multiple strips of masking tape to length and shape at the ends then lay em over the dome then cut along the edge this creates?

SAS

 

[propologist]

i have used contact paper with things printed on it as a guide before

 

[darthinvictus]

Use a compass with a sharpie mounted in it to create the 2 layers of rings you will need than the tape idea should work to get the gear spacing.

 

[jackdoud]

How many do you have? If you've got a spare you could make a single tooth template and use it to trace the pattern on. For sizing just do some geometry to work out your diameter and then divide by the number of teeth.