Ingestible Cannabis Oils

Hello all!
I am currently caregiver for my girlfriend who suffers from some serious eye-ailments.

Getting to the point here; we have had success with treatment by smoking high-thc varieties and I would like a little help with info on direct ingestion of extracts. I'm familiar with cannabis-butter/oil edibles like brownies etc. I've also had some previous experience making a glycerin tincture that worked quite well.
I would like to ask you though if you could help me with any links to information regarding the science/manufacture of some extremely pure, edible, high-thc cannabis oils.
We've found that BHO works well when smoked but as i'm in a non-medical area of the states it is very hard to find affordable and reliable supply without making it myself. Much of what i've encountered is not purged well enough that I can, in good conscience, supply it as a medical-grade treatment to my partner.
What i would like to do is manufacture my own steady supply of high grade cannabis flowers, medical quality smokable extracts, and ingestible cannabis oils.
I would greatly appreciate any help or guidance you may offer me in all of these aspects but especially the ingestibles as many of you seem to be much more well-versed than I in that particular science.

I thank you very much and eagerly await your reply.

U can make Rick simspon oil but I would use a high proof grain alcohol instead. It's very easy to make.

Although I make oil I mostly make chocolates with, see Fadedawg's link for extracts, an easy way to ingest is a brownie recipe. Take 2oz high grade bud, run it through a coarse-mesh kitchen screen. Then run it through a fine mesh oil-splatter screen, 12" wide and flat over a large bowl. This comprises half the flour. Take care to save and include the finest dust. Melt 6oz. unsweetened chocolate with 3/4 cup butter or oil of your choice. Add this to the large bowl with the sifted material. Add 1/2 cup flour, 2 cups sugar, 3 eggs, 1 tsp vanilla, and one cup of chopped nuts or coconut. Optionally add 1-2 teaspoon of flavoring, coconut with the shredded coconut or almond extract with slivered almonds, or just peppermint or orange extract with the chocolate, you get the idea. Although not part of a standard recipe, I add couple of tablespoons of water to thin the mixture a bit. Spread in an 11" X 17" cookie sheet, and bake for 25 minutes at 350°F. Let cool to room temp and cut into 100 equal size brownies. 4-5 brownies a day, 3-4 hours apart, provides a decent baseline level of medication.