93EXCivic MegaDork
4/11/13 7:15 p.m.

So I am going to attempt to make composite body panels for the Yugo. I have worked with composites before but I have never attempted to make a mold off an existing part before. Could any point me to a good how to on making molds particularly off existing parts?

mike53 New Reader
4/11/13 7:30 p.m.

Found this while



kevlarcorolla Reader
4/11/13 7:53 p.m.

Making moulds off the original parts is pretty easy really,just remember that the mould will be in the exact same condition as the part used so do the prep to the steel part as if it was ready for paint.I did the entire body of my AE86 years ago with no experience at all,adding a front air dam and rear wing was easily done with wood and filler before building the mould.I made the entire front end as one mould and part then simply cut the hood free AFTER the part was mounted to the chassis-much easier than trying to align multiple panels. After the prep was done I did 3 coats of release wax and too be safe 2 coats of water based PVA,only had a problem seperating with the roof mould due to a negative casting I didn't pick up on around the windsheild/rear hatch opening. [URL=http://s117.photobucket.com/user/kevlarcorolla/media/DSC00384Quicke-mailview.jpg.html][/URL] [URL=http://s117.photobucket.com/user/kevlarcorolla/media/CopperCorollaProfessionalPic.jpg.html][/URL]

JThw8 PowerDork
4/11/13 8:29 p.m.

On page 2 of my very un-updated Yugo thread there's some step by step of me pulling molds off the hood


Of course if I ever get off my butt you could just wait and borrow my molds, then you get fender flares too ;) Too bad you aren't closer, between the 2 of us we could mold the whole car pretty quick.

44Dwarf SuperDork
4/11/13 8:35 p.m.


ronholm HalfDork
4/11/13 8:36 p.m.




Dr. Hess
Dr. Hess UltimaDork
4/11/13 9:19 p.m.

When I get to messing with the, it's going to be with plaster and burlap fabric for the mould.

93EXCivic MegaDork
4/12/13 7:09 a.m.

Awesome. I am going to take a swing at making a mold for the hatch first.

4cylndrfury MegaDork
4/12/13 9:07 a.m.

www.Sollercomposites.com - good customer service, a lot of selection, good prices

And, dont get too involved in making the molding process too complicated. Some time ago, I wanted to make some intake parts from composites. The 2 things I was most interested in was a MAF adapter and Intake tube. The tube turned out kinda rough, chalk that up to inexperience. But the adapter turned out pretty good, because I broke it down into easy to swallow chunks.

I made the tube part using a tub of spackle as the pattern - it was just about the perfect size, and had a little draft to (hopefully) introduce some venturi effect that might speed up the intake charge somewhat. I made that part by itself. Then for the mounting plate, I simply laid up about 4 layers of fiberglass cloth on a flat surface, which resulted in a 8"x8" flat plate of rigid composite. I cut out the attachment plate out of that flat panel which made getting the shape right much easier.

Resin will offgass somewhat as it cures, so its best to wrap it in something to compress the layers and avoid curling/delamination during the curing stage, and also to force out uneeded resin to reduce weight and increase density (strength). I did not take this step, again because of inexperience, which resulted in some unwanted defects, but a crude yet effective DIY method was published by MotoIq.com using a pattern they cast from RTV:

When the 2 pieces were done curing, I sanded them a bit to get them a little more uniform, and simply used some more resin as glue to fix the 2 pieces together. Ignore the tube in this pic, it was a hot mess. The adapter however, is still in use today, about 4 years later.

I know its not the same, since youre talking panels, and I was working on much smaller fiddly bits. But the methodology is about the same. Some panels may be tough due to shape or location. Break the panels up if need be, composites are pretty forgiving if youre creative enough. They only require a few general rules be followed.

sanikaorient New Reader
6/12/14 7:26 a.m.

I totally agree with you ,for more information about fiberglass and it's manufacturing can find at http://www.sup E36 M3l.com/protection-covers.html

nicksta43 UltraDork
6/12/14 7:46 a.m.

I would like to thank this canoe for bringing back this post. Good information.

I really like that maf adapter 4CF. You said you used resin to join those two pieces together. Did you just use straight resin or add some strips of glass for strength?

1/6/19 4:50 p.m.

Hi all, 

Could use some advice.

I would like to use the bumper pictured as a plug for a mold, and make a new bumper out of glass.

Would you recommend doing a one piece plug/mold, or cut off each end and do it in 3 pieces?



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