UPGRADE!
I got my 2ml sprayers yesterday. They need no spray volume modding as they only spray a tiny amount, at most 2 drops at a time. This is small enough to be attached to a regular ecig. The one pictured above has a retaining ring I made from some aluminum from a pop can that goes through the battery case. It looks nice and keeps it secure but it isn't strictly needed.
I was going to write up a how-to with pics, but it's so simple to do the pics shouldn't be necessary.
What you need:
The sprayer- I found them on eBay, about $5 shipped for five. Get the 2ml variety. I have some 4ml ones coming, but I don't know if they will be too big or not yet.
A tiny bit of plastic tubing to attach the bottle to the cart - I used the same bit from the prototype, it came out of the $1 hairspray bottle. It was the feeding tube. Below is the internal length of what I used.
A cartridge - one you don't mind drilling. Type isn't important, at least on the 901. I was able to mod a single piece cart and one of those double piece carts, the procedure is basically the same. The one pictured above is the two piece variety.
A drill with a bit that is slightly smaller than the tubing you will use so the tube will fit tightly and not leak.
A sharp knife to cut the tubing. A hobby knife is best.
Procedure:
Drill out the sprayer nozzle with your drill, straight through the sprayer hole. Go deep enough to give enough room for the tubing to insert, but don't pierce the back of the chamber.
Drill a hole in the cart. Take the filling out first. You want to drill directly into the bottom of the filling chamber so when you pump the sprayer it pushes the fluid from the bottom of the cart towards the atomizer. On the two piece cart, you want to remove the cup and drill through the outer shell. Once you have done that, reinsert the cup and drill through that, using the outer shell hole as a guide. Make sure to drill into the cup on the flat side.
Cut your tubing. The length depends on what kind of ecig you're attaching this too. For an OEM e-cig, the tube will be fairly short and when it's assembled you won't even see it since the bottle will be flush with the cig. For a battery pack use like mine, it will probably be longer. Make sure you have spare tubing handy if you cut it too short. You will want to cut the end that goes into the cart at an angle so it elongates the hole and saturates the filling better.
Assemble! Insert the filling into your cart, and then press the tubing into it as far as it will go. Press the other end into the sprayer as far as you can. That's it!
Fill the sprayer and pump it a few times. Check for leaks and make sure the filling is getting moist.
Congrats, you now have an e-cig that doesn't need to be constantly taken apart to be refilled! Just give it a pump or two when the vapor goes down, but not too much or you will get flooding and juice in the mouth like a normal overfill.
Keep an eye out for my NEW mod coming soon - the UPAC!