Jack, roll the pieces out with an extra 2" for each end to be joined,
i.e. 4" if you are joining the two ends of the same piece, like a
bagel. The ends to be overlapped should be fatter than the
mid-section. Overlap the ends and place your palm over the overlap;
roll the overlapped ends on the counter under your palm until they
are the same thickness as the midsection. This will increase the
length so you may have to practice a bit to get the final length right.
When I make bagels I roll the dough as described, wrap the dough
around my hand such that the two fat ends are overlapped in my palm,
roll in short strokes to keep the rest of the dough from twisting too
much. The seam should almost disappear. The shaped bagel ends up
with about a 3" hole at this point. By the time it is boiled and
baked the hole is down to .5" to 1".
Werner