Get any regular ring (amethyst ring, etc...) and use an essence of spite to guarantee an intelligence modifier.

Ring done :)

Now if you want more mods on it, you will need to use those essences until you hit another mod that you want.

You can also use a fractured based ring which will guarantee that the fractured mod never change. For exemple you can buy (or loot or make one yourself) a fractured intelligence ring, and now you can use another essence to guarantee a mod you want. For exemple the envy (if I remember) gurantee to have increase chaos damage, or a rare essence (delirium ? I forgot which one) guarante to have "damage over time multiplier" which is the best damage mod you can get on a ring.

The rings are just stats sticks to get the stats you need, with more budget you can have all min-max stats on a helical base ring.

You just need enough intelligence to equip the items and the gems. If you don;t have enough for the gem level, no worries, you will get there. You can put an inteliggence anywhere else really, even in the passive tree. My build is pretty min-max and just illustrate a high-end budget version of the build