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Custom Carbon Fiber Briefcase

This blog will chronicle my attempt at making my own custom Carbon Fiber Briefcase. This is something that I’ve wanted for years and years, but the only ones commercially available are ridiculously expensive. As much as I might want one, there is no way on earth I could ever justify $2000+ for one. And honestly, that’s a ludicrous price, as I know what the materials cost.

My goal is to construct a fully carbon case, similar to the “Zero Halliburton” one pictured here. I did not want to go the cheap route and simply “wrap” an existing case, or even worse just do flat panels and mount those in a standard shell, which are really ugly. I wanted to go all out and make a proper fiberglass mold to create my case halves the right way. I’ve got most of my materials ready to go and started on some preliminary steps.

Below I’ll document my efforts, and hopefully I’ll have a cool carbon case of my own, for an order of magnitude cheaper.

Let’s start with some of the basic materials. I decided to approach this the following way: Get a cheap briefcase to use as a mold, and to borrow the hardware from. Modify and adjust that case as needed to get the details I want. Create a fiberglass mold of that case. Layup carbon into that new mold. Finish and clearcoat the two halves. Drill out holes and apply existing hardware. Finish the interior with fabric/pockets/etc.

So, let’s begin!

I scoured eBay for the cheapest briefcase that would fit the bill. I wanted it black so that the hardware was black, as silver hardware on carbon would be ugly. I found a decent specimen for $25 (and free shipping) and while I’d never use it as-is, it should perform well as a molding plug. It actually is a giant piece of junk.

Next, we need some basic materials. We’ll be needing fiberglass fabric and mat for the mold making, carbon fabric, epoxy, polyester resin, gelcoat, and some basic tools. I’ve worked with carbon before and have made things like knife handles, grips for my gun, a copy of an RC Car body, so I generally know the process. The mold making will be new, but there are a lot of good tutorials out there on the internet, and Youtube is useful.

Here’s the fiberglass fabric and chopped strand mat I got from US Composites. (While their site is a bit wonky, they had real nice service).

I get my carbon fiber fabric from eBay. There are several quality sellers on there that will get you as many yards as you want at very good prices. I got 3 yards of a very nice 2×2 Twill fabric, which should lay up very nicely and give a fantastic look.

I use West Systems two-part epoxy for the carbon layup (with the 105 base and quicker 205 hardener). It’s high-quality stuff and works well, and isn’t horribly expensive. You can pick it up online, or most marine supply stores sell it as well, since people with boats often need epoxy.

Now to the case. I removed all the hardware off it and set that aside. Had to rip up the interior foam panels a bit to get to the screws, but I’m planning on doing something different anyway, so that’s not a big deal to me.

The case was really cheapo, and had an annoying “ribbed” panel on the bottom. I don’t want to reproduce that detail, so my first step was to mix up a nice batch of epoxy and put a flow coat to fill in all that detail. Once that is set up, I will sand it smooth and then can work on other details I want.

Was looking around for other styles of case, just for inspiration, and hit this nice one. Looks like a collectors item from Nissan, for their GT-R.

After a night of curing of the first epoxy coat to smooth out the primary surface, I started working on some details. I decided that I wanted a very slightly raised “X” pattern on the case. This will give it a little dimension, and also give it slightly more rigidity. I figured that an easy, controllable way to achieve this was to use simple masking tape to create the lines of the X, and would cover this with additional coats of epoxy to give me a sandable surface with the profile I want. So I worked that up, covered with epoxy, and let it cure.

Came back this morning and added some additional tape lines to create a smooth profile into the higher area. More epoxy, and once this is done I can sand and finish the top. I’ll then be able to fill in the various holes, and after that is smoothed out I can start waxing and get the gelcoat and fiberglass on.

Did a little more work and some finishing on the case over the weekend. I wanted to add in a little more detail, so I embedded some washers in the center and corners. Once these are cleaned up and more sharply defined, they will give a slight molded detail at the corners that I think will be pretty interesting and look slightly industrial. I still have a lot of sanding and filing to do to get everything as smooth as I want. The better I can get this part, the cleaner the mold will be and the less work I’ll have to do later. My gelcoat and final fiberglass supplies should show up today, so I’ll be ready to go pretty soon.

Finally got back to work on this. After some more finishing and sanding I started on the actual mold-making process. First was to wax the plug thoroughly. I used carnauba wax and put on about 6 coats. I had done some reading online and one expert fellow had good results using standard hairspray instead of the expensive PVA mold release agent, so I just misted on a few coats of that too. After that had all dried up nicely, I put on 2 coats of gelcoat. DAMN does that stuff stink. I was used to the nice odorless epoxy so that was a nasty shock.

I think my coats were a bit thick, as I used a brush, so we’ll see how it turns out. I’m not expecting perfection so I think it will be OK.

I let that cure up, and last night I put on the first layer of fiberglass strand. I’ll put on another layer of that in the next day or so and will let that cure up for a good long time. It’s cold here, and things are taking a bit longer to harden. After that, I can (hopefully) pop off the mold and start the fun carbon stuff.

Here’s the fiberglass mold. This consists of two coats of gelcoat and two layers of fiberglass strand matting. I let that cure up for about 3 days before prying it off the mold plug. Let me tell you, getting that mold off was HARD. Due to the way the case was designed, there was a slight lip at the bottom edge that ended up getting gelcoat under it, which required dremel tool action (that dust is nasty), prying with various tools and generally a lot of effort. Took about 40 minutes of heavy work to get that out.

And here’s the mold! I need to do some fine sanding and polishing to get the surface real nice, but it came out remarkably well. A little bit of hand work, a few coats of wax and we’ll be ready for the fun part! I’ve got my carbon fabric all ready to go. I’ll just need to do a couple experiments on some scrap pieces to see if my twill fiberglass will be ok for some inner layers (I don’t want the white fiberglass to peek through the carbon weave).

I got the fabric pieces cut and ready to lay in. I’m going to try using an outer later, then two extra layers on the edges where the hinges will be, and then a second main layer. If that’s not strong/thick enough I will add one more edge strip and a final cover layer. I use blue painters tape when cutting the fabric. This helps to not only get your edges straight and measured properly, but also prevents the cut edge from fraying. Depending on the weave, if you start to get a loose edge it can ruin an entire piece of fabric, so it’s best to secure those edges. The painters tape works well because it peels off pretty easy, so you can keep the fabric piece nicely intact, lay it into the mold, get a little epoxy on it to get it stuck down, and then peel off the tape edge and finish wetting the fabric.

After waxing the mold, I applied a little bit of epoxy to give the fabric something to stick to as I laid it in.

After about an hour of work, I got the fabric into place. There is a full size piece, the long sides have two additional strips that also go through the corners, and then a final full size piece forms the inner surface. Doing the corners was tricky, the radius is really tight and the fabric had a tough time wrapping up into it. I think it will be OK though. This cured overnight and I started the process of getting it out of the mold today. Much like getting the fiberglass mold off the plug, this is proving to be a challenge, and I think another 15-20 minutes of prying and pulling will get it out. After that, I’ll probably do a fine wet sanding of the outer surface to get it smooth and as flawless as possible, and then I’ll probably do a coat of gloss clear on it. I’ll have to see what the finish is like, it might look cool with a slightly more matte finish.

Got the case out. The form came out really well, but the finish is going to need some work. I think that the use of the wax combined with not having vacuum bagging made some of the epoxy retreat from areas and leave some holes that will need some fill. I think that the next steps will be to rough trim the flange area off, clean it thoroughly, then do a brief hand sanding pass. At that point, a very light coat of epoxy and filling in some of the holes will give a surface that can be finished properly. Then it will be time to do it all again for the other half!

Here’s the case trimmed up a bit. I left some water on it after washing it off to get the idea of how it will look when fully finished. I think it will be pretty darn sweet. I need to figure out how to fill in some low-epoxy areas, but it’s getting there.

Took the case pieces to my friends house last night and we used his Bridgeport to trim the edges of the case halves and get them perfectly flush so they will match up and close nicely. Sure is nice to have the right tools. I'm honestly not quite sure how I could have accomplished that precision by hand. Now that the halves are dimensionally OK, I need to do the sanding and finish work before I assemble the hardware.

Cutting with the Bridgeport

Got the case halves back and they match up pretty well. There is a slight variance at the corners, but on the whole it should work pretty well. I'm going to be putting a thin rubber gasket around the edges, so that will mask any of the couple mm difference.

At this point I need to do a lot of finish work to clean up the carbon finish, and then it's a matter of installing the hardware. Fun.

Carbon case halves