Get yournself some 90+% denatured alcohol and grind up your stems very very fine as much as possible. Soak the ground up mass in the alcohol, enough to float it and shake every few minutes.

Then strain it and pour the liquid on a pan/glass plate. Let the alcohol evaporate (ALL the way!) and scrape up the resulting oil. Works best with a decent amount of stems.

I had 25 or so g's of stems and shake, got 1.1g of oil.

Love, my Lord