How to create a custom bucket?

I don't have any tutorials ready, but I think there were some older tutorials here already. Try https://mcreator.net/search/content?keys=custom+bucket

I got you man

make a bucket texture, but then make x amount with the texture of whatever liquid is picking up (milk, water, lava). You can just make a new layer, draw it on there, then do save as a new texture for each one. 
 

make it an item, and make the other buckets items. Set up a trigger where when you right click on whatever liquid it is, that it fills that block with air and then after it replaces the original bucket with the bucket that is filled with that liquid. Then when those buckets are filled with whatever liquid, make a trigger so on right click it places that liquid and replaces the item with the first bucket. I’m not very good at explaining this, but hopefully you can half get it. I haven’t done this, so it might not work, but I think it might. 

Can someone show his command boxes for tank filling part? I could not figure it out how to use custom bucket to fill cauldron properly.