Solas was built on top of a bodysuit. The bodysuit was spray painted with fishnets to make it look like scailmail. Craft foam made up the leg armor and chestplate (and all the armor pieces), and those were glued directly onto the bodysuit, including the pieces of the gauntlet.
All the details of embossing on the armor was done with hot glue, painted, and the armor pieces mounted straight onto the costume.