This summer, I'd like to visit quite a lot of castles in Wales. I'll be solo and don't (can't) drive an English right drive car. Just looking at a map and seeing where the major ones are, is this possible to do by public bus and train?

Two/three nights in the Black Boy Inn inside Caernafon Castle and visit
-Caernafon Castle
-Beaumaris Castle
-Snowdon Mountain Railway
-Penrhyn Castle

Two nights in Portmadog and visit
-Criccieth Castle
-Ffestiniog Railway Company
-Harlick Castle

Two nights in Llandudno and visit
-Conwy Castle
-Rhuddlan Castle

Three nights in Cardiff and visit these
-Chepstow Castle
-Tintern Abbey
-Coch Castle
-Caerphilly Castle
-Raglan Castle

Thanks for any advice you could offer.