Beginning with your whole coconuts, you're going to want to crack them open with a small hammer.*
The next step is to extract the coconut meat from the shell. To make this super easy-peasy, simply place the coconuts in the oven for 10 minutes at 325ºF/170ºC. You can then use a coconut tool to easily remove the meat. However, feel free to simply use a knife/ any sharp tool, if that's all that you have to hand.
The next step is to make coconut milk. To do this, you need to blend the coconut meat and filtered water in a high-speed blender for between 1-2 minutes. Although there will still be lots of coconut pulp, you'll find there is also a lot of coconut milk now too.
To separate the mixture, simply use a nut milk bag and allow the homemade coconut milk to gather in a large bowl. The remaining coconut pulp can then be dried out and used within all sorts of baked recipes.
Pour this coconut milk into a heavy-based pan and heat it on a low, consistent heat.** .
While heating, the water will evaporate from the coconut milk mixture. The coconut will begin to get crumbly in texture and solidify. This is when you'll begin to notice the oil separating from the solids. This process can easily take between 1-2 hours, if not more. So just be patient! (All good things come to those who wait, after all!)
Once the mixture has completely separated into the solids and the oil, simply gather all the solids and discard them. Then pour the remaining oil through a strainer, into an airtight container, making sure to press down on the solids to release as much oil as possible. This can then be kept in the fridge.
* You can then save the coconut water within to drink or use at a later point within smoothies, to make a coconut-almond blend nut milk etc.
** If you try to use higher temperatures, to cut down the time it takes to make this oil then you run the risk of ruining the oil. Unfortunately, high temperatures can (and will) change the composition and properties of the coconut oil. So don't be tempted to up the heat tooooo much!
Remember: Coconut oil will go solid when kept in the fridge. However, it remains fairly soft and will melt again at warm temperatures.
I think it's also worth noting that this oil can be gathered at an earlier point in the recipe too. Whereas I have allowed the coconut solids to brown, thus colouring the oil and yielding an oil that is more-often used within hair & beauty applications (although it is still edible. It will just have a stronger flavour, which I happen to like!). I have also learnt that if you turn off the flame just before the solids begin to brown and leave the oil to still be gently heated for a further 10 minutes or so, then you will have a 'water-like' clear oil that is more neutral taste-wise.
Recipe on Alphafoodie: https://www.alphafoodie.com/diy-how-to-make-virgin-coconut-oil/