This isn’t meant to be the definitive PCB etching post. I don’t have any experience etching boards and was hoping readers could contribute their best/favorite methods for etching boards in the comments.
We’re linking to Tom Gootee’s page on toner transfer etching. The first step is to print the design on glossy paper using a laser printer. An iron is then used to transfer the toner to a prepped copper board. The board is then soaked in etchant to remove the exposed copper. The printer toner is mostly plastic and resists the etchant. Once the board is etched, Acetone is used to remove the toner. Tom has been keeping his site up to date and as his research progresses.