How to make Cannabutter out of a 1/4 OZ?

Hey first time "chef" here, long time smoker lol. I have a quarter ounce at my disposal to make a batch of brownies out of. I will be using mid-to-high end and unofortunately will not be able to use more than that. The recipes I seen online are all for the butter. I want to do the oil method via double-boiler I seen in another thread. I have tried search but didnt really find too many details and the specifics on measurements. Could anyone point me in the right direction?

Specifically:

What type of Oil... Corn, Veg, Olive
How much oil to MJ ratio?
Is it the same with butter also?