[christofoo]

I'm new to bodywork, and I'm having a hard time getting started on my "big" aero mods (front bumper and tail). I'm a physicist, and I am pretty handy with a range of different DIY tools (esp. woodworking, home improvement, and electronics). I feel like some of you with more aero bodywork experience could help steer me. I've read a ton, but without the experience I just don't feel it coming together, and I've already had a couple false starts.

My goals:

• I want it to look good. My 6th gen Civic sedan is the one that really needs mods. It's actually my wife's car, and she demands that the mods be svelte. In particular I think the corrugated look is not okay where it gets noticed.
• I want my mods to be cost-effective and time-effective, but:
• If I end up with some low-tech molds that I can re-use, I think it would be cool to do some short-run "production" and sell my mods. But I don't have to. To understand me better, if a good-looking fuel-efficiency body-kit were available for the Civic for much less than $1k, I would buy it and be done (my time is precious to me). On the other hand if I could spend 200 hours becoming a FE bodywork master and be the one to produce that product and make a little money doing it on the side, that would also be worth it to me. Is it worthwhile?

Here are my thoughts on non-molded approaches:

1. Minimalist: Grill blocks and air dam below the bumper in coroplast (or lawn edging for the air dam). I think this is not the ideal nose configuration for efficiency, it won't lower the point of stagnation as much as it should due to the curvature of the bumper, and I will still need better tricks for the wheel skirts and tail.
2. "Sports" body kit (front bumper and skirt): should result in some fuel-efficiency gains, but requires grill modification, and in the end would not be optimal. Also I think the fact that the front is lower than it ought to be will mean that scraping will be more severe than it ought (correct me if I'm wrong, I think the "sports" bumpers are lower than optimal). Overall I think this doesn't rank highly for cost-effectiveness, although it ranks well for time-effectiveness, but not really because I still have to learn some bodywork tricks for the rear wheel skirts and tail. I'm also hung up on the look. Obviously some folks love it, but I'm not one of them and I'm not enthused about meeting ricer chums.
3. Reinforced coroplast methods with added "finishing". By finishing I'm thinking a layer of hollow-bead-filled epoxy, sanded and painted, to eliminate the corrugated look. For reinforcing I could use metal or corrugated strips underneath, and/or fiberglass before finishing. Not sure though, maybe the fiberglass is necessary to make the system hard enough so the finishing layer doesn't crack. Possibly I could search for a finishing layer a little more flexible than epoxy, and yet it needs to be hard enough to sand. Bead-filled Liquid Nails?

My thoughts on molded methods (as I currently understand them):

1. Molds: I like foam for ease of creation. (Easiest for male molds, just use a straight hot wire.) But if I want the mold at higher temperatures (thermoplastics) I should maybe switch to woodworking. I've also thought about coating a foam mold, i.e. brush on plaster, sand it smooth. Plaster over foam might crack though, maybe silicone would make a better high-temperature top-coat, but I don't think silicone is sandable. Mix silicone with a filler? Filled liquid-nails?
2. Fiberglass: to me the primary drawback of fiberglass is the number of chemicals I have to safely master. Just feeling a little chicken here. Also if I want to reuse my molds and do some short-run production, fiberglass layup will take a lot more time per unit than thermoplastic. Check me; does fiberglass tend to be around $3-5/sq-ft including resin after you apply the required 3-4 layers?
3. Simple-curve thermoplastic: if I can avoid compound curves, then I can form the thermoplastic without a vacuum fixture. Mcmaster has a temperature-controlled heat gun which I think would be good for this purpose. Not sure about a hair dryer. As long as it's a simple-curve, I could use a foam mold and use a sheet of something to protect the mold from the heat. A sheet of silicone would be re-useable. A sheet of corrugated plastic could probably be formed together with a solid thermoplastic exterior and the two could be glued together to form a stronger double-layer.
4. "Frame molded" simple-curve thermoplastic: use "frames" instead of molds. I.e. construct a re-usable frame where the curves are created by metal conduit of the desired diameter. Use the heat gun to apply heat from the inside of the conduit. I just had this idea. I think it would be perfect for tail-end stuff. Not so much on the front bumper where I need to match the curves on the car. Hmm. The curves could be multi-layer for strength, and the straight panels could have bar reinforcement.
5. Vacuum forming: Probably my favorite idea for compound curves and short-run production, but I imagine making a vacuum fixture for myself would be a bit of a pain. Anyways I'm questioning whether compound curves are needed.
6. Is thermoplastic ever much less than $2.5/sq-ft? I'm looking at 4x8' 1/8" sheets of PETG on McMaster. Any pointers on the best thermoplastic choice would also be welcome. I think ABS might have better qualities, at least for simple-curves, although it costs more that PETG. (Admittedly, I have a local plastics supplier I haven't quoted either material yet.)

Sorry, I know this type of post has been repeated, but not everyone's goals are the same. I'm at that point where I've tried to help myself but I think an expert leaning over my shoulder would help.

Thanks in advance,
Chris