I've played through Arcanum once as with a Gunslinger/explosives-build, it was fun.

For my second playthrough i want to be a Charming smoothtalker businessman with goals to get rich.

"Born in one of the richest familys in Arcanum i was excluded from the family's wealth by my father for spending too much of it and plotting to have him killed to inherit his massive wealth, i now find myself as the only survivor of the crash.

So now, with a priest who thinks i'm a newborn god and the possibility of scamming myself rich by going along with it, i slowly work myself up the ladder of wealth, through my knowledge of people and psychology, money and gambling, i will get rich and powerful."

Just a background which i will roleplay, he doesnt have a lot of empathy and just wants to get rich and live life to it's fullest,
not really evil but he will do what has got to be done to make his coinpurse heavier.

I'm thinking of going with mechanical tree and alot of followers, other than that i'm not quite sure how to build this character.

Does anybody have any advice?

Maybe you have made similar characters that you can describe.

Many thanks

Besides the usual choices (enough dexterity to wield a weapon, and enough skill to not drop it) here are my recommendations:

1) Charisma. Needed for ranks in Persuasion, and for maximum followers.

2) Persuasion. Needed for the talking quests, and to be able to join the Thieves Guild.

3) Thief skills, especially Pickpocket. (Protip: steal valuable items rather than gold; gold is limited to 100 per pick.)

4) Haggle. Buy cheap and sell dear. Expertise also allows you to sell anything to anyone, meaning that the Herbalist will give you top dollar for that weird thing no one but the junk dealer would otherwise want.

I'd also consider playing as a gnome. They get a bonus to initial reaction and to Haggle (meaning you can get to expertise and/or mastery with a lower investment in WP). Then if you wear a smoking jacket and/or cast Purity of Water on yourself before starting a conversation, you can sucker— I mean, charm the shopkeepers (and everyone else) as much as you like.

Don't forget to join the Thieves Guild. Their quests pay pretty well... though not quite as well as camping in the wilderness for random encounters of the two-legged kind. After all, armor and weapons — even bloodstained ones — fetch quite a pretty penny. Heh heh.

Haggle Mastery is pretty fun, since you can even buy items characters are currently wearing/using. It's also one of the easiest mastery quests - maybe the easiest.

You could play a build like this without any thieving too.

You need not focus on magick or tech for a character like this, but if I were going to pick one it would be tech, since you'll be able to craft items and sell them for absurd profit, and the ingredients you have to buy to make things will also be cheaper.

While the haggle skill fits your RP build, I've found little use for it. I just use Magnus to make goggles (lvl4 mech tech) and sell them for serious profit. (150-200 gold investment and sells for 854 gold) Having Jayna make fatigue restorers is is also nice for early cash.

Consider the other use for Haggle: to sell anything to anyone.

You don't have to lug stuff around, trying to match it to the right buyer.

You get a better price for arrows from the herbalist than from the general store.

Everyone else pays better for junk than the junksmith.

Likewise, everyone else (besides junk dealers) pays better for magic items than the gypsies.

[Minor spoiler] Here's a practical use: all that stuff lying around in the Crash Site cave and the Bessie Toome mine can be redeemed at the general store and/or blacksmith (possibly over the course of several days) for more than enough money to cover the cost of a serrated chakram from the Shrouded Hills gypsy. Boom! Now you have a weapon which is more than capable of taking down the bridge thieves, grizzly bears, putrid rodents, rock golems and random members of the Molochean Hand. In fact, it becomes my go-to weapon for the bulk of the game, until I get a chance to complete the Throwing mastery quest.

Protip: You can go to a gypsy, quicksave the game, have her identify a magic item and then see what she'd pay for it. This will tell you whether a given item will sell better if identified or not. In general, if her buy price isn't at least 100 gold higher (to account for the identification fee) then reload and leave it unidentified. Remember not to actually sell it to her; you're only using her to gauge the market.

True. If you don't think Haggle is worthwhile, try going back to playing without it after you've played with it. I always get Expertise in it just for convenience.