Thoughts to consider.
Will the object need additional supporting to stand?
Will it be mostly Three dimensional, such as a Turks head knot?
Will it be "used" in anyway other than decoratively?
There are ways to supplement the knot(s) that could be invisible.
Depending on the actual tying, which by the way, will help us help you if you were to disclose what they are, I am going to venture that a stiffening agent such as "mod-Poge" or thinned wood glue will handle the needs.
The previously mentioned thread, by Transminator, should give you plenty of decisions to make. ;-)