I've built and rebuilt boats with System 3 epoxies. No, they're not cheap. But, they pretty much last forever. And, they're stronger that you might imagine. The wood will fail long before the epoxy will even think of bending, if mixed correctly. Plus, you don't have to wear a respirator while working with it. Another boat builder buddy of mine couldn't believe I was actually laying fiberglass when he could walk in my work shop with out a respirator. We talked and drank beer the entire time I was glassing a hull.
If this was me, and it might be one day, I would:
1. Prep the bar top by sanding smooth.
2. cut little wood circles to fit into bottle caps.
3. epoxy wood circles into caps.
4. epoxy caps and wood circles to bar top. Cap side up.
5. create a barrier around bar top.
6. check level on bar.
7. check bar is still level.
8. warm epoxy in water bath.
9. mix and pour epoxy.
10. STEP BACK, leave the room, RDWHAHB.
Let me clarify a couple points here:
After sanding, dust, then vacuum, then wipe bar down. Tack rag is okay but a plain cloth can be used in a pinch. The less dust in the area, the better the finish. And, go change clothes. You have sanding dust on your clothes, it WILL get into the finish. Go change.
The little wood circles in step two fill an empty space in the caps but also give you a way to glue the caps down. Otherwise, they'll float to the top of the epoxy, even as it cures. Cut these in a separate place from the bar. I would do it with the wood circles instead of just gluing the caps down so that I had a sharp edge to the caps with no glue visible in the ridges. And yes, I really am that anal and yes, you will be able to see the all of the ridges.
Create a barrier: the epoxy WILL drip and run. There's no way around it. And, if you don't have some kind of barrier, it WILL glue your bar right to the floor. Read that first paragraph about the wood failing before the epoxy does. Now, if you have a raised arm rail around your bar top, you've got a barrier. But, most bars do not have that arm rail on the server side. Here, you can clamp or screw a temporary barrier. And the secret: Use plastic, like painter's drop cloths, between the epoxy and your temporary barrier. Saran wrap will work in a pinch but a thicker plastic is MUCH better. The heavier/thicker the plastic the better, but it has to be smooth. Any wrinkles in the plastic drop cloths will leave marks. Even the manufacturer's folds will leave marks if not pulled tight enough. BTW, those plastic drop cloths aren't really as smooth as they look and you might still end up having to lightly sand the edge but it will keep the epoxy from sticking to your temporary barrier.
Check level. This is critical because even a sixteenth of an inch will be noticeable in the finished top. Go ahead, check level again. Then, check it again just before pouring.
System 3 epoxies have a very good flow rate, but if you warm them by placing both jugs in a warm water bath for a bit, they will flow just like water and fill every one of those little crinkles on the sides of the caps quite easily.
Mix and pour: Wear old clothes. Wear old shoes. Wear gloves. I buy a bunch of the yellow dishwashing gloves at the dollar store. You will have to change them before you get done. Gloves are cheap compared to what you're doing.
DO NOT mix the entire amount of epoxy at one time. You will never be able to get it mixed well enough fast enough. This epoxy is exothermic. When you get a bunch in a container and it "kicks," it gets HOT. Yes, it will melt the plastic bucket right in your hand and pour right on the floor. You did put one of those plastic painter's drop clothes under the bar, and on the floor, didn't you? Yes, it will get hot enough you can't hold onto it.
I've used this epoxy a LOT, and I use the red plastic cups to mix. USE A NEW CUP FOR EACH MIX AND POUR. Cups are cheap. And, once the epoxy kicks, if you try mixing another batch in the same cup, it'll kick before you get it mixed. Use the BIG craft sticks from Walmart to mixing. Once you pour from a red cup, drop the stick in it and reach for a new cup and stick. Do not put this on a good table. It will glue itself there for posterity. Have a lined trash can you can just pitch the spent cups into or set them on plastic on concrete.
I would probably line up a bunch of cups with four squirts of part 1 in each, and a stick in it already. Then, all you have to do is hit two pumps of part two and mix. Or, have a helper.
For a job this size, buy the pumps. They are WELL worth the money. Depending on your local temps, choose the hardener with the longest cure time. Heating the epoxy with the water bath will speed kick and cure a bit but if you work in smaller batches, it won't be a problem.
Also, buy half again as much epoxy as you think you'll need. You will lose some to the mixing cups and spills, etc. Much better to store the extra in the garage than not have enough to finish the bar top.
Now, one of the biggest rules: once you start to pour for the bar top, DO NOT STOP. Let me say that again, DO NOT STOP the mix and pour operation on the bar top. Do not get another beer, do not have a smoke, do not go pee.
Mixing in smaller batches makes for a good mix and cure but it also takes time. You have to keep moving because the only way to get a good smooth finish is to get a progressive cure going from one side of bar to the other. If you stop mixing and pouring you will get cure lines from the different rates of cure from each pour. But, if you keep moving right along, one pour will bond into the last pour and the lines won't be there.
You're really only filling the spaces between the caps and just over the top. You probably don't need more than a 5/8ths inch depth between the caps. That'll give you about 1/8th on top of the caps. And yes, that should be enough but you can go a bit thicker without a problem.
Once you pour the last cup, do a good visual check that all is well and it's not running onto the floor, then leave the room. Seriously. You will be tempted to look close. Then you'll be tempted to touch. If you touch it, you WILL have a fingerprint in that epoxy for life. Then, you'll think, "Oh, it's been a couple hours, I'll just go check." And, you'll want to touch it to see if it's still tacky. Yup, it is. And now you have a fingerprint for life. Really, get away from it and lock the door. Or, you'll end up sanding out fingerprints. Now, it's okay to pee.
There is an advanced technique of using plastic for a mirror smooth finish with no sanding. If you've never done it, don't try it here.
Once cured, this will last a lifetime. Though, if it gets any real exposure to UV, you should slap a bit of varnish on it unless you picked the more expensive UV resistant epoxy.
If you have ANY flaws, the entire top will need the same sanding the flaw takes. Then you can use a very light brushed on coat of warm epoxy to hide that damn fingerprint.