TIG welding is ideal for stainless steel/steel mounts. I have almost exclusively made object mounts (16years + experience)from stainless steel ( 304 316 grades and their variations) I have welded down to 0.5 mm orthodontic wire (very difficult but we did it) and as a general rule most of the armatures made were fabricated using sizes ranging from 0.9 mm to 50 mm dia wire/rod /solid bar ,8mm -100mm dia tube (1.2,1.6mm wall), pipe, flat bar and sheet. TIG is fast and clean and when bead blasted with glass bead , gives an excellent finish ready to use for display,contact points with the object using small diam rod can be done with silicone tubing, Most major museum institutions in Australia have their mounts fabricated in Stainless Steel. The Ability of any welding unit to do thicker Material is its amperage and a very good machine that I used in a previous Job , which was a fair price, was the Duralloy 201PFC TIG AC/DC pulse inverter welder. It was easy to teach the novice and the one we had was reliable and had the advantage of being able to weld aluminium also. You can easily weld without any fancy pulse and programable capability in the machine , but I think the packages available are such a good price that its worth the cost and can make good welding better. High frequency start is a must. I am a bit of fan of Speedglas welding helmets as they are relaible auto darkening helmet that you can weld literally all day without a problem ( One business I worked for would do the entire object mount fabrication for museum institutions with more than 3000 objects, so welding was a major compnent of the job). Cheers