Need a matching rug to protect an area of carpet around a fireplace, external door, pet bed or other source of dirt? It's a lot easier to remove a rug and clean it than having to clean the whole carpet, and if there's a complete disaster (like a log falling out of the fire) it's nice to know that it's the rug that will suffer and not the expensive carpet.
Or maybe you just need a small mat for the bathroom or kitchen and don't want to spend a lot of money. Anyone who's ever had a carpet fitted has probably kept a few offcuts in the attic "just in case", so why not use them?
The only other things you need are: some PVA (polyvinyl acetate) glue - often sold as woodworking glue or craft glue, and available in large quantities very cheaply from builders' merchants and DIY stores; a carpet knife; a small paintbrush; and an indelible pen. If the rug is not going to be laid on another carpet then you will want something to make it non-slip as well - see Step 3.
Step 1: Cut the Rug to Shape
Decide what size and shape your rug should be. In my case, I wanted a semi-circular rug to go in front of a disused fireplace, with a section sticking out at the back to fit right under the grate and protect the pale-coloured carpet from the soot that sometimes falls down the chimney.
If the shape is complicated, you might want to make a paper template first from newspaper. Otherwise, just draw the outline on the back of a spare piece of carpet using an indelible pen.
Think about how to position the shape on the available carpet, particularly if the rug is going to go on top of the carpet it is made from. The pile will need to run in the same direction as the carpet around it or it may look a different shade, and you should aim to match the pattern if there is one. A rug in a doorway will look odd if the pile runs at an angle across it, even if it is laid on a different floorcovering. Whether the carpet is woven or needle-punched, it should be possible to tell by looking at the pile side and/or the underside which way its "straight grain" runs.
Cut out the rug. This is best done from the underside using a knife so as not to cut the pile. Pull the cut piece gently away from the surrounding carpet to minimise pile loss.
Step 2: Seal the Edges
If you just used the rug as it is, bits of pile would come adrift from the edges in use and when you vacuumed it. It would soon look quite tatty with the backing becoming visible. The cut edges need sealing.
Tip some PVA into a dish or jar. Don't water it down unless it is very thick, you want the glue to soak into the backing of the carpet and the base of the pile without dripping everywhere, but do this outside or over old newspapers just in case. It's also a good idea to find something like a stool or a cardboard box that is a bit smaller than your rug to put under it, so that it is supported but with the edges overhanging for easy access. Lay the rug over the support with the pile side uppermost. Try to keep the edges straight or they may dry with a permanent curl.
Dip the brush into the PVA and work around the cut edges, applying glue to the edge of the backing material and the base of the pile all along the edge. If you can get underneath and apply some PVA to half an inch or so of the back around the edge too, so much the better, particularly if the backing is a material such as woven hessian which is prone to fraying. (That won't be necessary if the back is foam or rubber.) Be fairly generous with the PVA - it dries clear so it won't be obvious - but keep it off the top of the pile because it will make it stiff and hard.
Rinse the brush when you have finished. Leave the PVA to dry, preferably overnight, then apply a second coat.
Step 3: Non-slip Treatment
A rug that is going to be laid on a hard floor will slide around unless it has a non-slip backing. Perhaps your carpet already had such a backing, but otherwise you will need to treat it in some way. The most obvious solution is specialist non-skid rug paint, or for a small rug you could use the rubbery liquid that is sold for use on the soles of homemade slippers - find it in big haberdashery departments.
Many people swear by silicone bathroom sealant, hot-melt glue or ordinary rubber cement such as is used for patching tyres, so try them on a carpet offcut if you happen to have some. You probably won't need to cover the whole surface of your rug, just do a few squiggles.
Another possibility is to buy a non-slip shelf liner, cut it to shape and stick it (try PVA again) to the back of the rug.