I’ve made boxes with paper and pencil and a calculator and a port length calculator from a web page on my iPhone lol. I write my own spreadsheets, though. It makes my OCD happy to have everything exactly the numbers that they are. No rounding off or anything.
Tuning and box size for woofers can be very difficult to determine. Some t/s are hard to read, and you don’t always know the type of suspension a woofer has, and that makes the t/s read differently, even though you can sometimes spot certain suspension types by the ratio of certain t/s parameters
There’s only so many combos of woofer types with the available design styles. So to get the best volumes, you gotta know how the combos of parts in a woofer are acting relative to other woofers with their t/s. All of the style changes show up in the t/s. It takes a while to learn what they actually mean, like intuitively so. Even then, you have no idea who tested them or what the state of the woofer was during testing. You just have to understand why some woofers look the way they do and how they’re made to perform.
4th orders are more about the sealed then anything. People make 4th orders like they make SPL boxes. Idk people act they don’t understand sealed boxes sometimes. Sealed boxes have properties that change the whole system. The rear chamber in a bandpass is always the most important one, and you need to make sure that woofer will actually do what you want it to in a 4th. Or at least understand how to make the box the best way to get it the way you want. I learned 6th orders because sometimes 6th orders are superior for certain applications. Some subs just do better with a port. Sometimes it’s a hard decision to make lol.