There are many reasons one might want to brush-on cyanoacrylate (CA). And it is entirely possible to dispense some glue onto a brush or the workpiece and spread it using a stand-alone brush, as one would with paint. But it is more convenient in many cases to have a brush applicator, so i will show you my simple way of creating one. I'm sure you can take the concept and make it your own through customisation.
     The fundamental concept for this instructable is to use heat shrink tubing to clamp the brush's bristles in place, and also clamp this 'casing' or ferrule to a glue dispensor, channeling the glue onto the brush head.
    The glue has to be able to flow through the brush head. For this reason, the applicator might only be useful for thin (non-viscous) CA glues. However using thicker bristles in the brush head may aid movement of thicker glues between the bristles.

Before we get to stepping, here's what you will need (also pictured):
- Cyanoacrylate glue with a nozzle tipped cap or lid.
- Hair of some sort for the bristles
- Heat shrink tubing (a.k.a. “heat shrink”; or just “shrink”) used in electrics and electronics
- scissors
- point heat source such as a cigarette lighter
- sewing thread.

I have an instructable on making (paint)brushes. The following steps are a foreshortened version of the instructions from that source, since the process is the same. You may like to view the full brush instructable though - https://www.instructables.com/id/Make-brushes-such-as-for-painting/

Step 1: Prepare the Parts

Select a bunch of hair at least four times as long as you intend the final bristle length to be. The bunch should be about half as much as would fit into the heat shrink tubing you're using, since you're going to double it over. I use my own hair because i have lots of it. But other options such as horse hair will work.

Cut a piece of heat shrink approximately 40 mm (1 1/2 or 2 inches) long. The heat shrink that best suited my glue bottle's tip was "2.5 diameter".

Cut a length (about 200 mm) of thread. Ideally this should be some man made fibre, since CA reacts with cotton exothermically. However cotton can be used.
Like ravenking, I wish I had seen this sooner! Better late than never. I have made brushes, but used the wrapping with thread method. Thought I was pretty smart, until I saw this. Like every good ible, it makes you say, why didn't I think of that! I love the simplicity and using what you already have. I am not going to use this for glue. I have an unwanted vine growing in rose bushes my Dad planted. As he is gone, it is so important to me to take care of them. Using your 'brush applicator ' I can target only the leaves of the vine with an herbicide. So, I thank you so much for sharing!!!
For a single drop or a few drops use a PLASTIC Q TIP and cut the end off at an angle. Use something you don't care about like a small jar top or ? and put a few drops of glue on it and dip the Q Tip cut end into it. Carefully touch the drop of glue that will be clinging there to your surface. If you find you need more just be careful not to add too much and to not add your bling or whatever you are attaching in advance as this will get the glue on top instead of underneath. <br> <br>Make sure you do NOT set the Q Tip down on anything you care about! Have a newspaper or something there to dispose of the used pieces. <br> <br>A sewing needle can come in very handy to position tiny things here and to scooch any protruding drips out of the way or off. Needles work better than pins as often the ends of pins are slightly bent and will not make things sit right.
This is a good idea. I wished I knew about this before I glued my crystals on my watch bacause the glue was so watery and sticky it got all over the top of my crystals and made them look like muddy goop. At least I know for next time. Thanks.
You could probably get away with dispensing a little drop, or puddle, or cup of glue and dipping the crystals contact surfaces into that? But then i guess that too would work better with thicker glue than thinner.<br> Glad the idea is helpful.

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More by balisticsquirel:Brush applicator for cyanoacrylate glue Make brushes (such as for painting) Cyanoacrylate (CA) glue storage and dispensing using syringes 
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