PO butchered out a hole for front mount cooler,pretty nasty job.
Have the steel but need to know best way of making a pattern ?.
Click to view attachment
Not the best pic but most will get the idea,TIA.

Use painters tape to make a pattern across the area, remove the painters tape in one piece and lay it on the fresh sheet of metal

Cardboard and sharpie

Card Stock and pencil

Tape as suggested and cut it out with exacto and transfer to metal

Unless you are after a proper restoration, I would trim more from the upper edge of the cut-out to eliminate the remnants of the stock round holes. And then make a paper template after that.

Thanks to all for the quick replies ,brent made a good point about prep trimming which I have to do for the replacement piece anyway,good spotting .
Still haven't worked a way to stop sparks going into the trunk ,thinking about cardboard with high temp silver tape which I have and aid that by an old wet towel nearby .... ???.

Got a bit done yesterday,found a part roll of foil building paper and built an enclosed area inside the truck, worked a treat for keeping sparks @ bay.
Carefully worked away @ this and ended up with a pretty tidy job (I think) ,had to straighten the panel at the bottom where the remnants of the grommet holes were as I didn't want to cut any lower.
Only downside is the patch will need to be folded slightly inwards @ the bottom and then curved to fit the shape of the car.
Decided not to use cardboard or tape but will cut a patch and bolt it on using the spoiler mounting holes I can mark it then reduce the fit for my but weld clamps.
Click to view attachment

The weather had held me back but now getting hotter and much improved,cut a patch and got a reasonable fit witch was hard because wanted less gap than those crappy but weld clamps which I didn't use for setup as the cap is too big.
Do I need to sand back the galvanizing on my repair patch @ the weld points ?
TIA.

I like to use C.A.D for templates (Cardboard aided design)

Didn't use carboard as compound curve so it didn't work for me,cut the repair panel and bolted it on as mentioned and profiled to the hole,however the welder was way smarter than me (electronic ) and only got good welds near the end cause have little or no experience in welding panel steel.
Last build I did after buying this machine was building a heavy single axle farm trailer and used 5mm thick box section,so easy on verticals a great machine.
End result was a little messy but will clean up ,mostly enjoyed getting that "education" after years of welding heavy stuff.
Click to view attachment

[quote name='porschetub' date='Nov 14 2022, 07:21 AM' post='3041159']
[quote name='Nacho' post='3039485' date='Nov 4 2022, 01:32 PM']
[quote name='porschetub' post='3037721' date='Oct 25 2022, 04:19 PM']
PO butchered out a hole for front mount cooler,pretty nasty job.
Have the steel but need to know best way of making a pattern ?.
Click to view attachment
Not the best pic but most will get the idea,TIA.
[/quote]




Click to view attachment
[/quote]
All cleaned up with light skim of filler to tidy up after leveling off the welds with my new Dremel copy rotary tool which for the money has been a real asset .
Real pleased with end result for huge hrs spent which is not an issue as I have retired as of Oct this year.
Take my hat off to the guys doing rustorations ,the welding is quick but getting patch panels perfectly profiled and with least gap in is very challenging, I feel blessed as my car is not rusty.
Click to view attachment
Cheers.

@porschetub - Very nicely repaired.

+1 excellent repair panel.

Any chance you are located in the NE and have an extra couple of weeks?