Fab help, how to make a hood?

**guizai** · 01-04-2007, 05:08 PM

Hey guys, I'm trying to make a hood for my screen but I'm having a hard time coming up with the best way to start out. Below is a pic of what I'm trying to accomplish, ala newer BMW's where they have a sort of second hump and hood over the navi screen.

Which way should I do it?
1. Make a mold out of spray foam and then covering it with fiberglass?
I assume that with this method I could spray, let it dry, then cut/scrap it to the appx shape I wanted.

2. Make a wood/mdf skeleton then cover it with fiberglass?
I want the hump to have a bulbous look rather than be concave, I'm wondering how I could accomplish that by stretching fleece.

FWIW, that's not my car either, I just got a pic off the net.

The end result I'm just going to cover in vinyl to attempt to match the rest of the dash.

Any help, suggestions on how to proceed would be totally appreciated.

**GoHybrid** · 01-04-2007, 05:21 PM

check out my thread "Working with Foam" That should help you get whatever shape you want. As for foam choices, i would not recommend spray foam. Just doesn't hold it's shape properly. Use a rigid foam like blue or pink EPS as found at Home Depot, if not an actual prototyping urethane foam.

You may want to consider making a female mold out of fiberglass and then pulling a male part from it. That can save you alot of time finishing and will allow you to pull multiple parts easily should you decide to try something different.

If not, just make sure you use a good mold release when you're applying your fiberglass, and that part should come out nice and clean after you do the sanding thing.

**guizai** · 01-04-2007, 06:02 PM

I saw those posts, excellent work.

Just to re-iterate your post:

SO what I could do is buy the pink foam, glue a couple stacks together, shave and cut it to the desired size, to the size of the item I actually want. From that I'd make a female mold using fiberglass. Once that's cured, I could go ahead and line the inside with fiberglass (all the while making sure I have good releasing agent in between) making the "male" piece which should be the same size and shape as the original foam piece?

**GoHybrid** · 01-05-2007, 12:46 AM

you got it man. there's lots of little intricacies to properly preparing a plug to create a mold with, but nothing too extraordinary. Let me know if you need any help.

**guizai** · 01-08-2007, 12:24 AM

yo Hybrid, I've got some flower foam to start this project but the pieces are not that large so I'll need to glue two or more to get the desired size. Any suggestions on glue? I tried some 3M Super 77 but it's not tacking up enough to stick the pieces together.

**GoHybrid** · 01-08-2007, 02:20 AM

man... that's such a soft foam. the problem you'll find is that if you don't glue it with something equally soft or softer, you run the risk of getting glue lines that either won't sand out and leaves you with visible seams, or worst case it tears out a chunk of foam if you snag a chunk of the glue layer. What I would suggest if 77 isn't working is try using just a SPOT of superglue/activator in the center of mass... that is to say as far away from where you're likely to sand. Freeman supply has a fast cast urethane called repro ultra light. That's probably going to be harder than the foam you have but i wonder if you couldn't mix in some microballoons (i believe west system, #410 or #402... can't remember) to make it even more sandable, you could try that. Otherwise just go light on whatever you do use. 5 minute epoxy might be another thing to try.