From the very witty Canadian Style Guide (1997):

2.03 Nouns with adjectives and participles

a) Hyphenate noun-plus-adjective compounds (in that order), whether used attributively or predicatively:

duty-free goods
tax-exempt bond

b) Hyphenate noun-plus-participle compounds regardless of position:

snow-capped mountains
a time-consuming activity

Exceptions

There are a number of them, including handmade and handwritten.