Someone actually proved (at least up to the extent that hhyyrylainen deemed it acceptable) melting metal underwater (The Holy Grail: Hhyyrylainen’s Challenge of UC Metalworking Completed and Formalized with 47 Citations!),and then telekinesis could be used to shape the metal to prevent warping and whatnot
Or telekinesis users could just use telekinesis to remove the water from an area and then smelt metal as one would on land ig