I want to create some bike lugs for my specific geometry using 316L and 3D printing. What is the thickness of traditional steel lugs? Are there any other suggestions on this build?
I have handled quite a few lugs of different types. Some are cast and some are made out of pressed sheet steel then curved and jointed shut to make the 3D shape. Other people create a fillet joint in the correct size tube (where the ID fits the OD of the main tubing) and cut the lug to their own design.
Most of these are 1mm thick, or less, though some of the cast ones I have seen are thicker. I don't think they are very expensive, so you could order up some basic examples from a framebuilding supplier to have a play with, or cut up an older frame to see what is going on within.
Have a look at this website, which is well stocked with nicely presentled examples. https://framebuildersupply.com/collections/lugs/products/top-lug-for-standard-1-frame-extended-top-31-8mm-headtube-and-25-4mm-top-tube-73-5
I have used a UK distributor called Ceeway in the past. While they have a great selection, they don't have such pretty pictures on their website.