Depending on the kit it shouldn't be too difficult, Hubbard had a very good manual. I'd contact the kit maker as they should have a solid idea of time involved. One thing I'd like to mention is pay very close attention to the marking out and drilling, even nut pin spacing is absolutely critical to even voicing. Also, be prepared to ask for help regulating if you have multiple string choirs and expect voicing to take a long time if you haven't done it before, it's not like a piano and determines touch as well as sound. >
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