Toolmaker's hammer with a magnifying lens. Derek Winks made one of these. His plans can be found here:https://www.homemadetools.net/homema...maker-s-hammer
https://s3-us-west-1.amazonaws.com/h..._with_lens.jpg
Previously:
https://www.homemadetools.net/forum/...477#post158605
https://www.homemadetools.net/forum/...029#post140886
https://www.homemadetools.net/forum/...911#post124702
https://www.homemadetools.net/forum/...986#post133913
https://www.homemadetools.net/forum/...710#post118689