Hi and welcome. I am a mekkie from way back, and I love them. However, I will also tell you plainly a regulated mod is easier and safer to use, like by a lot. If you're using a Petri you're already a coil builder, which is a step in the right direction as rebuilding the coil is the only way to regulate the vape on a mech. I assume you already have an ohmmeter in your coil tools; if not, you need one. A clear understanding of Ohms Law and battery safety is necessary--before you begin-- to use a mech without blowing yourself up.
It's a bit hard to advise you as I don't know if you want a box or a tube mech. However, it's super easy to blow a ton of bucks on top quality iron, and learning to use a mech well is a long and often frustrating experience. A lot of people give up and go back to regulated mods because they're so easy to do. Therefore I suggest you start cheap with something like a $15 clone Nemesis from Fasttech. Once you climb through the learning curve, and decide you want to do it for real, that's the time to blow $250 on that Kennedy Ruby, or a Rig/Roughneck, or a G-Paps.
I can not stress safety enough. The only safety on a mech lies between your ears. Buy good batteries-- Sony VTC4s or LG HD2Cs-- from a reputable supplier, and remember counterfeits abound. And don't build a 1-battery tube below .5 until you know what you're doing.
