Practical matters

Hi Folks

I'm soon to start on a Harmonic Canon. I had thought of a hammer
dulcimer but the designs I've seen are really quite complicated so I'll
go with ol' Harry's stringbox which is just within my reach.

I have three 8" x 36" x 1/4" spruce tops that I want to make into one
large board. Before I just glue and rub together I wonder if anyone has
experience of this type of craftwork and can offer some tips. The tops
are best quality and expensive and I don't want to botch up the job.

I'll be stringing the canon with 31 plus steel strings going from
(roughly) 22s to 14s, bass to treble, so there's a slight bass to treble
difference in tension, but not as much as on a guitar. Any advice on
struts and bracing would be useful. Thanks in anticipation

Kind Regards