I use the Elmers Epoxy resin regularly...in fact, just finishing up a cowl for my latest build using the stuff.

kzaiser is right...it's a bit thicker than most. However, I tend to prefer that, since I figure that I can always thin the stuff up, or leave it thicker, making it pretty versatile.

Here's some tricks I've picked up along the way:

1) Alcohol, as mentioned above, is the "standard" thinner. I mix about a capful of alcohol to 3-4 ounces of Elmers resin...though, that's by no means exact....whenever I'm doing the basic layup.

2) Another VERY powerful thinner is acetone. Do be sure, however, to read the various warning labels...acetone's good stuff to be careless with. Use it in a WELL ventilated area, and keep it away from any ignition sources. Its major advantage over alcohol is it tends to stay "in solution" with the epoxy a fair bit longer...meaning, the epoxy stays thinner longer, allowing more working time. Note, however, it also tends to widen the gaps between epoxy molecules a bit more...so you'll get a lighter, but not quite as strong, coat.

My normal process with the Elmer's goes like this (please note, this is for casting external parts on a plug, not laying up parts inside a mold)

I'll make my plug, wrap it with masking tape, and then coat the plug with cold vaseline (insert rude joke here). Then, I'll lay a layer of cloth on the plug, and liberally coat it with alcohol-thinned resin. At this stage, I don't do a whole bunch of smoothing or anything, but we don't want globs of epoxy for obvious reasons. A regular cheap paintbrush seems to work best here for me.

Next, when that layer is still tacky, but not "wet", I'll lay the second layer of cloth down, and then coat it with acetone or alcohol thinned resin, depending on how concerned I am about weight, and how smooth I need the part to be. Acetone thinned resin = lighter, smoother, but less strength.

I let the part then cure for a day or more, until the shell is nice and hard, and not tacky. At that point (and this is where I like the versatility of the Elmer's) I'll mix up a very small amount of Elmer's resin with no thinner at all...in fact, depending on the situation, i might even mix some West's microballoons in to make it even thicker. This I spread straight on the part, no cloth, and then use various tools (a foam roller works VERY well for the finishing touches) to squeegee/roll/spread the epoxy as thin as I possibly can. This last step fills in any gaps in the weave, as well as any minor depressions, etc, that may still exist. The trick here is to work quickly (the elmer's will go off in about 20 minutes I've noticed) but forcefully...you REALLY want a VERY thin coat...mash it down GOOD with that roller, etc. You're not looking to build any strength, and the straight resin can add weight in a hurry...you just want the thinnest layer possible to fill in the weave.

Once that's done and cured for a couple days, I'll usually shoot the part with a LIGHT coat of primer right away...for me, this helps highlight any areas that may still be rough, or need filling/sanding, etc. Again, I'm not trying to prime the part, just highlight imperfections. From there, fill/sand/finish with your preference of paints and fillers.

By no means is this the only way of doing things, but it IS a method I've had some success with using the exact same cloth AND resin you're using.