Sentence:  Unless a boy is a very good carpenter, and has great patience and plenty of time at his command, I cannot advise him to attempt making a built model,—at all events, not until he has formed several <WSD>"cut-outs</WSD>" first. One of these "<WSD>cut-outs</WSD>" will serve as a model or form from which he may frame his "built vessel," with such modifications as he may deem necessary. 
Meaning of the word marked with <WSD> tags:  A piece cut out of something.