The most basic tuba design uses three valves, found in instruments like the Besson BE1077 Performance Series 3-Valve Eb Tuba. With the fewest valves, they're the simplest to play, and great options for beginners or hobbyists. There are some drawbacks to this accessible layout, though: the range isn't as big as it could be, and some of the notes are slightly imprecise. That's no big deal for casual play and junior bands, but for more advanced settings, there are two ways to make a great Eb tuba even better. One is a compensating system, which cures the precision issue and can be found in lots of instruments here. The other is by adding valves, which improves intonation, improves range at the low end, and even helps with playing trills.
So which of these Eb tubas is for you? A straightforward 3-valve starter horn, a pro-grade model like the Willson 3400S Professional Eb Tuba, or something else altogether? A quick look through this section brings up all kinds of interesting suggestions, including some specialty designs such as the all-rotary Miraphone 283B Norwegian Star Series 5-Valve 4/4 Eb Tuba. Any of these tubas could be the perfect instrument to make your own, so don't worry about coming to a decision right away. Take your time, do whatever research you need, and make sure you're going with the best personal fit - do that, and you're sure to make a solid choice.