Ritual Converter, Variant (5e Feat)
From D&D Wiki
Prerequisites: Ability to cast spells, usage of a spellbook
After long and expensives studies of spells, you have learned to use them as rituals, which take longer to cast than usual.
-You can now transform any spell into a ritual spell, by writing it into a spellbook of any kind, by using 200 gold per spell level (to a maximum of 7) halve of your own level, to experiment with the spell and 50 gold to copy it into said spellbook. To convert and copy the spells you will need (10^level of the Spell) days, which can be accomplished by traveling, aswell as unocupied time. The spell will need 5 minuits more for each level. Cantrips can not be used that way. After the spell was converted there is a 25% chance you will not be able to use it as a normal spell anymore.
-You are able to add any normal ritual spell this way if you follow the rules above, yet spells that already have the ritual tag will only need 100 gold in total for each level. When doing this there is a 10% chance to not be able to use the spell as a non ritual anymore.