Ever since going to the Michael Smith workshop and seeing his 8x20's I have been fantasizing about a back of that size. I have a Wisner, which makes a 8x20 back for the 8x10, for $2k. What would the cost be to do it myself or have it done? Cost in terms of time and money? And would it be a matter of making it from scratch, after a trip to the lumberyard, or of finding an old back on a junk camera somewhere and converting it?