I have used metal stamps many times over the decades for work purposes but this set is for home usage. I purchased them to emboss plastic hard cases with pertinent information. I heat the stamps and melt info onto Pelican plastic cases for ID purposes. Tags or labels can be removed from my cases and I do not want to afford a bad guy the ease of taking a tag or peeling a label off my cases. I emboss the outside and inside with info.I do have a concern that the stamps may lose their hardness as what I do with them is similar to annealing metal. For safety reasons I'll probably only use these stamps for what I purchased them for and not stamping metal.