You know, this idea is probably just a common sense thing and I believe that may be something I am a little short of a lot of the time. In the past I always wondered,"where do I start my glue up on intarsia and how do I keep it from shifting a little at one place or another and leaving the last pieces out of wack enough that I need to tweak them to make them fit in". That was my dilemma that I found myself in on almost all my projects. They were all fitting perfect when I started but often not when I got to the final pieces. I just received 5 new patterns from JGR and included with it were a few tips about intarsia. She probably has been sending this same helpful sheet with her patterns for years but I normally do not read any of them. Her suggestion was to lay all your cut pieces on your backer board and make sure they are all tight and in perfect order. Then with all the pieces in place, carefully remove your biggest outside one and glue them on the backer board but not to one another. when you have them back in place against the other pieces on the backer board, let the glued one dry well in place, glued only to the backer board. After you have let the glue dry well and secure, and only then, you can remove the other pieces and start to finish gluing up the remainder ones in the same manner, except you no longer need to wait for the glue to dry during this phase. The advantage is, you have the glued and securely dried pieces in place and you now can glue the additional ones to them and work your way from your initial glued pieces, outward. By only gluing your new pieces to the backer board you will not have glue oozing out between pieces. I use a sticky glue for this and find as I push my new glued pieces against the previously glued and set ones, I am assured of a tight accurate assembly. I only need to hold my new ones in place about 20 seconds and the sticky glue will no longer be slipping out of place. The brand of glue I am using is 'Aleene's Quick dry TACKY GLUE'. I purchased it on Amazon. It only takes a drop or two and so far I have not had any known problems with it.
I hope that helps you, it sure has me.
Dick
heppnerguy