I HIGHLY recommend just buying new jewel cases. CD jewel cases are not fragile (compared to long box jewel cases). I have hundreds upon hundreds of PS1 games and music CDs that are 20 years or older in their original cases. Cracks and broken hinges are usually caused from abuse rather then from normal handling. Replacement jewel cases are fairly cheap, and they can use the original artwork and manuals. Unless your collection is really small, it's going to be a ton of work converting or creating artwork for different sized cases.
It's been common for people to take the time to create new artwork for different cases for Sega CD and Sega Saturn games (usually DVD size). This happened because those cases were truly fragile and up until recently, there was no easy way to get replacement cases, and even today, there is no cheap way to get replacement cases. The libraries for those systems are fairly small as well, therefore, the work to convert everything into DVD was seen by many as time well spent. However, since CD jewel case replacements are cheap and easy to find, there is no reason to use anything else. Again, that's my opinion, but if you plan to own a sizable PS1 collection, you will thank me when you realize how much time and effort you are saving keeping them in jewel cases.