Relining a guitar case can be a lot of work, but don’t let that scare you off. The results can be worth it as you are about to see.
I recently bought an old 1986 Ibanez RG530 Roadstar II. It came in a generic TKL chip board case. These cases aren’t that great but it served the purpose well enough. The problem I ran into was that the case and the guitar had been in storage for so long that the case lining had soaked up a musty nasty smell that no amount of cleaning or deodorizing could seem to remove. So my only option was to remove all the lining, seal up the chip board and reline the case with new materials. The following steps are the process I followed. I’ve never done this before so this was another learning experience, but it turned out fairly well.
This is what I had to start with.