Painting pro's need help with scallops

I decided to throw down some scallops on the tank of my new bike. I would like to use one big scallop SO CAL style but no luck. I have been in the garage for 2 hours trying to get them right. I have used a lid from a whipped cream container to help me mask the curve but I cannot get it even on both sides. Any help would be much appreciated.
Craig

 

Are you getting the shape you jneed on one side?

If so get a ruler and make some reference points around the scallop.

On this set of scallops I measured from the bottom of the tank to the bottom of the scallop, as yours is curved all the way along just measure the distance at the petcock or front mount or whatever and transfer that to the other side.

Make more measurements in this way, then take a piece of tracing paper, trace the scallop from one side.

transfer it onto the other (using the reference points to line it up) and cut it out.

If I've not explained it well enough I'll draw some pics. It is easy once you'e done it.

 

I'm no expert. I struggled with it for a while. Trying to get what was in my head to the side of the car was tough. I tried free handing with 1/8" tape but it never came out right when I backed away and looked at the overall design. I think you need the design on paper first giving you points that can be transfered to the full size object. The HAMB artists may disagree but this worked for me.
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Somebody on the HAMB came up with this design that I loved. I printed it out and used the picture to get the critical points transfered to the car. The points of the scallops and the the dish of the swales were marked on the car. Then all you have to do is connect 3 points at a time. Connect from one point to the swale to the next point. All you have to worry about is that curve. The overall look won't change. Then on to the next curve. All I needed to concentrate on was to match the basic curve of the picture. By having the points laid out the curves came out pretty close so all they needed was some adjustment. I didn't need to worry about the basic design.
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That's how I did it. I'm no expert but I am happy with the result.
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Thanks alot guys. I think my problem was trying to freehand it with pin striping tape. I think the paper will work great. I should not try these things at midnight. Tommy, your car is beautiful, again thanks.
Craig

 

Dig through your wife/girlfriend/grandmother's sewing kit and bust out the flexible measuring tape/cloth thing. Works really well for measuring your points and valleys for scallops.