Prepare your bag handle tube. Mine has been prepared using my favourite method detailed in a previous post.
The crucial equipment required for this method is (wait for it!) a piece of poly pipe usually used for garden irrigation and a length of wooden dowel. My pipe is 13mm in diameter, the dowel is smaller at 10mm diameter. Both are approximately 50cm long. It is helpful if the dowel is at least 10mm longer than the pipe.
Using a large stitch length, sew across one end of your handle, using 1/8" seam allowance. This is a temporary basting stitch and will be removed later.
Slide the irrigation pipe into the handle until it butts firmly against the end of the handle you have just stitched closed.
Now this next bit is tricky to explain. Working from the closed end of the handle, use the dowel to push against the irrigation pipe. The handle fabric should begin to roll back down over the dowel.
Work the fabric down over the dowel until the handle is the 'right side out'. This process honestly takes less than 30 seconds.
You should end up with your handle right side out with the dowel inside it. Remove the dowel. Either unpick the temporary stitching on the end of the handle, or simply cut the temporary stitching away.
To press the handle, I again use the irrigation pipe! Insert the pipe into the handle. Carefully press the handle with the pipe in it. The pipe helps to open the seam nicely for pressing.
This technique works perfectly for the handles I posted about earlier (approximately 1.25" wide, finished). If your handles are wider, you may need to use larger diameter pipe and dowel. The crucial thing is that the dowel has a smaller diameter than the pipe. The dowel should actually fit inside the pipe. Please don't hesitate to ask me questions if all this makes no sense to you!