...I have just read in The Complete Guide to Shadowboxes and framing objects by James Miller that when sizing the visible side spacers that there should be a gap between the ends once stuck in place to allow for the expansion/contraction of the wood. Will this gap not be visible there for looking a bit shoddy.
Page 62, caption for upper-left photograph:
"When making and cutting the shadowbox spacers to fit, remember to allow for slight expansion. If the spacers are too tight they will warp or come loose later."
The writer did not mention a gap, and the intention of that instruction was to avoid too-tight spacers that would warp or come loose later. More precisely, assemble the shadowbox spacers by gluing together strips of foam board and matboard. Cut the matboard strips precisely to make tight-fitting corners, and cut the foam board strips about 1/2" shorter than the needed length and center them on the matboard strips. Having the ends of the foam board recessed a bit allows the possibly-expanding matboard strips to push-in slightly the matboard strips which are perpendicular to them.
I hope that makes sense.
A related side note: When gluing the shadowbox spacers onto the deep rabbet of the frame, use ATG sparingly to hold temporarily and apply
dots of PVA or other hard-setting glue to hold permanently, as noted in the book's instructions. This practice holds them securely, but allows them to be easily popped-off in the future for replacement of broken glass (or whatever), and reused.
Do not apply the glue in long lines, as shown in the lower-right photo on page 62. Actually, due to confusion of the photos (which I did not catch at the time) the one used there is wrong; it depicts attaching the matboard strips to the foam board strips, and does not properly show how to attach the foam board/matboard assembled strips to the frame. Yes, I know it's confusing. Sorry.
