Creating a custom Bazooka tube style enclosure using concrete forms?

[omnibus]

I toyed around with quite a few designs in BB Pro but seems a concrete form tube would yield the best use of space and volume. I've seen a lot of people on YT that use these for sub enclosures (sonosub). My plan is to use 2 Sundown 8's on each end using a 10" concrete form. Then take a second concrete form and cut a section down the middle so I can fold it just enough to insert inside the other form along with some wood glue...that way I double the wall density.

So what is your opinion on using forms for enclosures? Are there resonance issues?

My next plan is to take an 8 inch concrete form and split it directly down the center of each side so it's in 2 pieces. I could then lay that piece on top of the 10 inch tube to provide my port so it's external. Will that equal the volume of a 4" port? Also if I cut my port hole in the direct center of the  10" tube so that the air exits in the center of my half piece of port where it will exit on each end....Bazooka does this on their dual sub tubes. Would this mean that I have to double my overall port length and wouldn't this basically act as a dual port?...I'm picturing that my hole on top of the 10" tube would have to be 8 inches diameter which is too big so how should I do this?..if not a good idea to have port hole in center of tube then would it work ok to just cut 4" hole at the end near one sub and seal that end of the port?

My alternative idea was to use an 8" sonotube and make an adapter with MDF but the sub won't have any protection and I'll lose some internal volume. Or just use 2 seperate sonotube's and stack them, held together with straps or whatever and use an internal port at the ends but that might be ugly.

[Triticum Agricolam]

So here are a couple things to think about.  When you go to buy sonotube it isn't all the size that's printed on the side.  A "10 in" sonotube can be anywhere from 9-11" in diameter, so bring your tape measure so you know what it is you are getting.   Because of this you can probably find two tubes where one fits pretty well inside the other.  

I'm not sure I 100% understand what you want to do with the port, but I can tell you this.  A 8" tube split in half is going to still have twice as much area as a 4" tube would.  If you have the port fire in both directions you will have to double your overall port length because its like having two seperate ports. 

[omnibus]

20 hours ago, Triticum Agricolam said:

So here are a couple things to think about.  When you go to buy sonotube it isn't all the size that's printed on the side.  A "10 in" sonotube can be anywhere from 9-11" in diameter, so bring your tape measure so you know what it is you are getting.   Because of this you can probably find two tubes where one fits pretty well inside the other.  

I'm not sure I 100% understand what you want to do with the port, but I can tell you this.  A 8" tube split in half is going to still have twice as much area as a 4" tube would.  If you have the port fire in both directions you will have to double your overall port length because its like having two seperate ports. 

Ok thanks. Regarding the port idea, When I said split in half, I was meaning down the radius and just using the top section..where it would look similar to what Bazooka did. Not that I'm emulating their look but rather the physical space . With how the port works, imagine a tube with a T in the middle. Bazooka did a dual sub version like that, I just wasn't for sure how well that actually works in regards to tuning. Also with port area, I was thinking that since a radius of 8" is 4" and the area of 4 is 50.3 ..then I multiply the area by the height right?

[bmwking]

4 hours ago, omnibus said:

Ok thanks. Regarding the port idea, When I said split in half, I was meaning down the radius and just using the top section..where it would look similar to what Bazooka did. Not that I'm emulating their look but rather the physical space . With how the port works, imagine a tube with a T in the middle. Bazooka did a dual sub version like that, I just wasn't for sure how well that actually works in regards to tuning. Also with port area, I was thinking that since a radius of 8" is 4" and the area of 4 is 50.3 ..then I multiply the area by the height right?

@Triticum Agricolam i imagine he means like this:

 

 

[omnibus]

^Yes, that's the design I was going for. I'm just not real sure how to measure that, figured if I cut down the radius it would be akin to a 4" port.