I use a small length of PTFE microbore tubing. Capaillay action draws it up and better atttraction to the plastic draws it out. For bigger jobs a pvc micropipette works but pressure from evaporatom can blow it out. If you don't release the bulb completely you can control the blow-out by releasing pressure on the bulb slightly.
Random ebay example http://www.ebay.co.uk/itm/333838705736?

It is always best to use capillary action to draw the solvent into the joint line. Apply the solvent to the back side or inside of a corner when possible.

Robert.

This may or may not be relevant but you never know.

Our mechanical workshop makes its own welding solution for perspex. Not that I’m suggesting you do likewise but it’s easy for them to get the chemicals from stores and we have fume cupboards. The pertinent point is they add small amounts of the plastic to be bonded to the mix which makes it thicker and less prone to evaporation.
You probably knew all that, if so sorry.

regards Martin

Michael, as a frequent user of plastic solvents I have found the best 'tool' for applying small amounts of solvent is a fine pointed but full bodied artists paint brush. The brush is held so that the solvent stays in the brush but allows capillary action to draw the small amount required from the brush into the join, i.e. not pointed directly down to the part. It doesn't need to be an expensive brush, the best I've found for shape and longevity are the 'Boldmere' brand from 'The Works' – quite inexpensive for what they are.

Super glue of course is another matter, the thin type will run everywhere if not controlled properly – a paint brush is of no use of course but a simple sewing needle reversed in a holder of some kind – mines in a pin chuck – with the eye of the needle outwards is. I have small slices of aluminium drilled with 3mm holes a few mill deep to act as 'inkwells' for the cyano. The glue is picked up in the eye of the needle and transferred to the part. – if you use the pointed end of a needle the glue runs back up the needle a short way and is impossible to apply. There are of course, commercial, photo etched, equivalent applicators available but a needle works well

Needless to say but be aware of where your fingers are – any solvent will quickly leave a fingerprint impression and the cyano of course even more quickly ensuring that the part becomes an extension of your fingers!

Many years back I bought one of the micro bore applicators – a very small hypodermic needle attached to a thin walled plastic tube reservoir. To use it's stood in a bottle of solvent to allow it to fill before using on the parts. The needle quickly becomes contaminated with residue plastic inside and impossible to remove and it stops working – it still sits in the drawer!

Best – Tug

I bought a litre of chloroform, the acrylic solvent, from Italy back in the day. Goods in free circulation and all that guff. Bought it on a whim because I had never seen it for sale before. It arrived nil problemo.

It sits in the shed waiting for the day when my need will outweigh breaking the seal

The immediate problem, of course, morphed into something different when I discovered that the plastic in question was [to all practical purposes] insoluble.

Yes Michael, I should have said about varying plastics but as you said 'plastic modellers' I thought you were meaning the part was styrene.

Some plastics simply will not glue with anything whilst others adapt to varying solvents/adhesives. Polyethylene springs to mind – far too waxy for any adhesive I'm familiar with.

Epoxy may be better on your part, especially if you can reinforce it with a small pin of some kind but even that won't always be successful.

Good luck with it.

Tug