Gnomish Cannoneer (Magitech) Pathfinder

[Failedlegend]

Yeah so my buddy is running us through an Eberron Campaign (using Pathfinder ruleset, no 3.5 stuff) and I'm trying to recreate an old class I could remember called "Ultimate Gadgeteer"....specifically the weapon they used called a Buster which is basically a giant beam cannon....thing Pirate Gunner+Arcane Archer+Science Fiction.

So anyways the closest I've come so far (with a little fluff and some house rules) is a Magus that wields a Flamethrower (change fire to force damage and melee weapon to ranged weapon and your set) because they can imbue their weapons with spells and with Kensai you get a free exotic weapon (again DM said replace melee w/ ranged so I chose "Beam Cannon") Now the question is what to take beyond Level 2 the only thing I can currently think of is the Gunslinger Archetype "Experimental Gunsmith"

My current plan is to take 7 Magus Levels (Fighter Training+Iaijutsu+Lvl 4 Spells) and 5 Experimental Gunsmith Levels (for Grappling & Vial Launcher) but that still leaves 8 levels to play with (assuming campaign makes it that far)

So any suggestions the only requirement is the big cannon and preferably Gnome as the race

Image for Reference:

[Failedlegend]

Update on plans:

 

- Increased Gunsliger to Lvl 7 for Deadshot/Targetting

- Considering "Musket" Master since most of its abilities say "two-handed firearm" not "Musket"..refluffed as "Magitech Master"

- Considering 1+ Level of "Mind Chemist" Alchemist to synergize with "Experimental Gunner" adding bombs to it

 

That would be 15+ Levels total so either I can work in a 4th class (if it fits the theme) or add more level to Magus, Gunslinger or Alchemist.

 

Any ideas for the last 5 Levels?

[nikolokolus]

Who knows, maybe some kind-hearted Pathfinder/Eberron expert will be along shortly, but this sort of feels like the kind of question you'd want to post on a Paizo board.