if you're hell bent on trying it here's what I would do.
Step 1. suck the .1 ml of fentanyl/alcohol with a syringe, then squirt it on to a clean plate. im not sure how difficult it is to suck it out, but once you figure all of that out and have the .1 ml on the plate let it dry, you can put under a lamp, it might help to have a fan blowing on it lightly, or you can put the plate over a pot of boiling water and leave it there until you have a caked on crystal/powder.. *
Step 2. once you have the dry mixture on the plate you should decide what dose suits you best. you are determining how much water to add to get the concentration you are looking for if you are planning on doing 100 micrograms that is like somewhere in the ball park of 50-100 mg of morphine, so make sure you know your body and tolerance before you proceed. chances are you wont be able to get all the fent out of the patch, but it's best to assume you did when calculating, that way if you're off you will take less and not more than you anticipated.
Step 3. so the next step is to dissolve the fentanyl in an accurately measured amount of water. if you want to do 100 mcg doses then you add 25 ml clean water to the dried up powder and dissolve it completely. you can do this with a 1 ml insulin syringe if you dont have a big oral syringe. an alternative if you want to take 50 unit shots instead of 100 (want to have room to drawback, want to decrees the chances of missing etc) then dissolve it in 12.5 ml of water. with this method of volumetric measuring you will be able to determine that a 100 unit/1ml shot will contain 100 micrograms fentanyl at the most, or if you only used 12.5 ml 50 units or half a 1ml syringe will contain 100 mcg fent.
I think 25 ml is the way to go because it's easier to remember; 75 units equals 75 micrograms.
if you dont want to i.v. it then after you've dissolved the fentanyl in 25 ml of water you can squirt each ml into it's own little puddle on a large plate or tray, then when it dries out each little pile will have at the most 100 mcg, but keep in mind 100 mcg is a barely visible dose, much smaller than a grain of salt, so this method is flawed. I would stick to the syringe method, if you can find a large enough vial (like the big saline ones with a rubber stopper to put your needle through) you can store it in that and then when you want a dose you can suck up the right amount of water, then you can back load it into a needleless syringe and squirt it up your nose, up your ass, or on to a piece of foil for smoking.
but really dude you need to be damn careful with your calculations. this is the formula for it, and bare in mind Im not a mathematician. total dose of fentanyl in patch = x, number of millileters of water added = y, number of mg per millileter = z
in this case x= 2500 (mg)
x/y=z
2500 / 25 = 100.
it's simple, just make sure when your storing the finished product it isn't exposed to heat or air, otherwise the water will evaporate and the solution will become more and more potent, making it potentially deadly to inject. for this reason if you try it you should keep track of how many ml you've taken from the main stash and measure it before you take your dose out, that way if it doesn't add up you will know the mixture is becoming more concentrated.
I feel kind of shitty telling you this. I think that's why so many people avoid getting involved with fentanyl threads, because no matter how careful you are if you're not taking it as prescribed your life expectancy drops substantially.
* an alternative to this step is to skip the drying part all together and just dilute the .1ml with your chosen amount of liquid for y. you may choose to let it dry first if you would rather not inject alcohol.
