The roughest surface I have ever used on a bamboo backing glue-up was the 40grit on my bench sander, and I have used all the common glues..save your money for that toothing plane, and get the tools needed for good surface contact.
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I use TB3, bicycle inner tubes to mate the surfaces and then clamp the assembly into your form, mold, caul, shape however you do it.
Rich-goes thru lots of glue