It's always a good idea to scavange for a load of things and to start with original clothes and modify them, the one item unique to Gasman is the kilt, the rest is all modded stuff.
Random metal fidgets (Avoid sharp edges!) and found supplies work well. A wooden cilinder with an empty can on it can be painted to look like an old stick-grenade and its cilinder sanded down for a proper handle look.
Ammo belts (If not illegal in your location! Important) give a gruffer look, but general bandoleers made from leather can give the same impression, and filled with painted lipstick dispensers or other sized things to give off the same idea.
Tatter stuff, find other odd things which "You might have found one day scavanging" and find methods of easily attaching these to your clothes as keepsakes or means of survival.
I can't press how important it is to carry your own fork, spoon and knife (Avoid sharpy edges! >.0) with you. Wasteland already wears your fingers down like hell as it is, you don't want to have to scrape the sand off of your found meal by hand and then pull it apart with the same fat fingers that you use for weapon maintenance, it's a quick way to become a dead wastelander.
I hope this helps! Let me know if you need anything else.