Try making a tincture with the strongest, most tasteless alcohol you can buy. I've made them with everclear pure grain alcohol, but in some states you can't get alcohol that strong and have to settle for vodka. Either of these should work fine for what you've mentioned.

A couple weeks of steeping with a daily shake or two should do it. Macerated herbs may take a little longer. Then filter the tincture several times through a coffee filter to remove all of the particulate you can.

You should then be able to mix the concentrated tincture with some PG or VG to create your own flavor concentrate. Maybe let the mixture breath with the cap off to allow some of that alcohol to evaporate. Plus, there's alway steeping your bottled mixture in a crockpot or ultrasonic cleaner to help meld and mellow the tincture.

Now, before you go trying to make a tincture out of everything, I'd encourage you to search to make sure it's actually vapable and not toxic, like nutmeg. Good luck!

For coffee:

Take a glass jar and put in however much PG base you want to use (I do mine in batches of 30mls. Take about 1/4 tbls of finely ground coffee per 10mls, like you would grind for espresso, and mix with the PG in the glass jar.

Place the glass jar into a small pot with water, making sure the water "covers" the PG (so the water level in the pot is above the PG, but not flowing into the jar). Mix with a sterilized stirring rod (I use 8" glass rods from amazon). Mix until the PG is completely combined with the coffee grounds. I usually put the heat to medium/low. You don't want the water at a rolling boil, but you want it bubbling. Once you think it is mixed completely (about 20 minutes of stirring) turn off the heat and let it rest in the hot water for about 5-10 minutes.

Then, using a funnel and coffee filter, pour the PG mixture into a 30ml or 50ml bottle. Strain the PG into the bottle. This is easily achieved by taking the edge of the filter, twisting it so it covers the pg/coffee mix, and squeezing it into the funnel. Once the grounds are nearly dry, remove the filter from the funnel and bin it.

Cap the bottle, shake it, and then put it into a dark chamber to age for 3-4 weeks.

If you do this, you can literally mix and vape the same day, as the flavor is essentially pre-steeped. I usually will split the coffee flavor into 3 15 ml bottles with 10mls of the coffee in each, and then adding additional flavors like caramel and cream.

Good luck!