Make 3D, Light-up, Twisted animal Horns!

Step 8 Painting with glitter paint/foam glue mix.

The glitter paint needs to be clear or translucent.  It has to be water-based.  I found that the kind of glitter paint that we bought, well, it looked and acted more like glue than paint.  Anyway, mix 1 part of water-based glitter paint with 2 parts of foam glue and 1 part of water.  Mix it well.  The reason for mixing it with a lot of foam glue is, I found that the glitter paint didn’t paint on well, on its own.  It needs a lot of foam glue mixed with it, or (as I found out) it won’t stick to the surface properly, or spread smoothly.  Add a little more water if necessary. 

Take a flat, soft paintbrush – the kind that looks a bit like a pastry brush, but with softer bristles – and paint the glitter paint and foam glue mix onto the horn.  Be extra careful of the crepe paper.  Don’t touch any part of the painted section – the crepe paper will joyfully stick to your hands, and pull away from the horns!  
Paint part way inside the tip and base of the horns, to avoid that paint or glue 'tan line'. 
Take a look at your paint job.  It won't look great.  It will look uneven and lumpy, and the definition of the rings formed by the plant tie will be lost. Easily fixed.  Clean the paintbrush and remove the excess water.  Take the damp (NOT soaking wet) paintbrush and go over the paint, wiping and dabbing it into the areas between the plant tie rings and mopping up the excess paint at the same time.  This will make the crepe paper cling to the plant tie, and give back the definition. 
Allow to dry.  It will go several shades darker when the foam glue dries and becomes transparent, and the colour of the crepe paper takes over.  Flecks of glitter, suspended in the paint/glue, will also become visible.  

After it's dry, paint a protective coat of foam glue over it.  I mix a little water with the final coat of foam glue – it seems to go on less lumpy if a little water is added.  A lot more glitter paint can be added to the final coat of foam glue, if the glitter effect is liked - maybe 3 parts glitter paint to one part foam glue.  It will adhere to the surface a lot better at this stage.  Allow it to dry fully; 24 hours should do it.  Afterwards, it can also be sprayed with 1 or more coats of clear acrylic varnish - leave to dry well between coats.  The spray varnish really brings out the glitter when sunlight hits it.

Now your horns can be installed on a costume head or headdress, or attached to a headband and worn over a wig, or over your real hair. 
The horns may not weigh much, but they're not small.  The upright variation of the horns are still going to get caught in the odd doorway.  And goat/ram/faun/demon horns, the kind that curve down over your back, are going to be subject to the pull of gravity - and maybe the pull of curious onlookers.  So they need to be well-attached to a strong headdress or headband.  One that's not going to fly off your head and blow your cover if you walk through a low doorway, or if some wally decides to make a grab for your horns.  
If the horns are going to be worn over a wig, or real hair, hold them against a wig head or a real head and mark where you need to cut some shallow scoops out of the bases.  This will make the horns fit better with the curve of a real head.