Illusionist paint finishes which imitate real materials can be very effective, but may be more difficult than you think. Take time to study the material you wish to imitate very carefully before trying your luck.
The techniques
Faux marble
Marbling is done quickly with a layer of glaze being introduced and worked on and then another layer added before the first has had a chance to dry – with the result that the colours bleed into each other. Veins are drawn as thin lines in a darker colour, using a fine brush, and then smudged with a rag, feather or twigs while still wet. Unless the surface you are marbling is black, it is best to work from light to dark, using several coats of dirty-white glaze with a little black or raw umber added. Varnish the painted surface to protect it.
Faux tortoiseshell
Tortoiseshelling is probably the most difficult illusion to do well. First you paint a base coat of yellow oil-based paint thinned 3 to 1 with white spirit or turpentine. You leave this to dry before painting on top a coat of varnish, thinned 2 to 1 with white spirit or turpentine, and tinted brown. When still wet this is manipulated with a brush into broken diagonal bands. Then dots of varnish are added between the marks, and lines of darker colours (black and burnt umber oil paint) are painted on top and softened with a large, soft, dry brush. Varnish when finished.
Faux wood
The basis of wood-graining is dragging, using a glaze slightly darker than the ground coat. Wood grains are faked by drawing a comb or dry brush through wet glaze. Knots are faked by using the edge of a cork and heart wood lines are faked by pressing pieces of string into the wet glaze. Look at samples of wood to see what sort of effect you want. Bamboo can be copied as well, either realistically or so that it looks obviously fake. The most helpful tip is only to try to copy bamboo on already rounded woodwork or plaster.