Scribing a sunroof

[BVC500]

So, I'm working on Tamiya's 500SEC, and wanted to scribe a sunroof. The Mercedes of the era had steel sunroofs. What would be the best way to scribe this? I'm worried about getting nice, round corners. Can anyone recommend the best tool or technique for this? Maybe temporarily glue a template to the roof and scribe around it slowly? Thanks in advance!

[JeremyJon]

I just use a regular exacto pen knife, in particular the blades which have had the very sharpest tip broken off, so it makes a narrow flat edge to pull sideways and scribe with
That being said, I go very lightly, making many many passes until the desired depth, and keeps my edges clean, always in a drag motion
Tape masking is to soft and edges will push out during scribing, so I prefer to cut & use a plastic sheet template for precise shapes, in the case of a sunroof, I'd make it a female template, for the scribing to follow against

[drunken monkey]

Template definitely.
I would avoid using a blade and opt for a sharp point/needle/awl instead as a point seems to offer you better control.

Once you have a decent enough score, I would switch to something like a PE saw and use the PE thickness as a sort of guide for the sort-of panel line.
If you have to use a blade, consider using one of these.


like the point/needle/awl, the shape of the blade seems to be less prone to slipping.

Of course, this is based on my experience. I tend to find straight blades like to keep going in straight lines when scribing.

[BVC500]

Thanks for the helpful tips guys! I think I'll practice on some spare styrene before I attempt to cut into the roof.

[935k3]

I like using DYMO brand plastic label tape for scribing lines, it's thick and has a sticky back.

[petesy]

What about photoetched templates? Something like this might be useful for the rounded corners.

http://www.hlj.com/product/BRFG516/Sup

For scribing tools, I totally swear by photoetched saws and scribers. Ever since I first tried them 7 years ago I couldn't go back to dental tools or back of #11 blade. They are far more precise and does not snag and break on the plastic like the tip of the blade does.