Here’s an idea (NewVape Universal Cab Cap), the cap bottom itself is already as “universal” as you can make it, the debate is how many holes & angle of hole/holes. Assuming the angle is not a factor, drill two straight holes, that are threaded, I know these are small holes, that might be the biggest drawback, but with two supplied tiny threaded plugs, one could have a carb cap with no draw, one hole or two. I’m sure the extra parts and machining would make it more expensive, but if folks want to use terms like the “one cap to rule them all”, then this gets closer perhaps. Watching Edwin’s videos and seeing his shop, I think he likes to deal with metal, (I also own a DCup and many of his other “metal” toys). That’s why I doubt it’s a option here, but a plug option of something like “silicone”, might work, but would most likely have to be outsourced.
Now as far as angles of hole or holes, first I believe the only way one could tell is with a see through glass setup. Those using quartz bangers with direction glass cab caps probably come as close to seeing the potential effects of moving the air at various angles, though it would be tough to scientifically record the various results, but I think in general you could make some logical conclusions.
I doubt anyone has the expensive equipment to see how hole angles truly effect the inside of a metal cup and cap, like my DCup. So who really knows? I know you can see balls moving, depending, when you pull the metal cap off, so you could perhaps experiment making several models with various angles and deduce something, in the videos I’ve see, the two hole standard DCup carb cap moves them fine. But like emmdeemo has documented, I saw a bigger mess and oil overflow and immediately stopped using them. I’m of the belief the 30mm Sapphire dish doesn’t need any oil distribution help. I only have experience with the DCup rig, so while it may be possible to create a single carb cap offering, certainly one that physically fits is no problem, but it seems logical with all the devices you make that the airflow may not be universal.
And as
@emmdeemo pointed out, one or two holes might not be the best in every situation. So if my crazy plug idea is not feasible, then why not offer them in both one and two holes, see which sells the most on limited runs, then either charge more later for infrequent runs on the press for the less popular model. You could perhaps do something similar on custom hole angles, since no matter what “single rule them all” design you come up with, you will never satisfy everyone.
BTW: I’m satisfied so far with my stock DCup carb cap, but my play with my own plug, like emmdeemo has written about. I doubt I’ll like pulling anymore then I have to with the stock two hole cap.
That’s my 3 cents, I’ll look at the final offer/offers and perhaps try one, but only after an emmdeemo review!
. Bumped temp to 490 and best soaked again for a min or two and took another. Now got both terps and 
![:\](/i/s/hmm.gif "Hmm :\")
