Just last night I made handles for a denim rag tote bag. I cut the handles 3" wide and my length happened to be 32". Remember these dimensions are for a tote bag so are longer than for a purse. Then I cut Thermolam batting 2 1/2" x 30".
The batting was centered on the wrong side of handle fabric. I then turned up on the ends about 1/4" - 3/8" to hide the raw edge. Then finger pressed the raw edges over the batting on the long sides of the handles, folded in half matching fold edges together.
Pinned to secure and then edge stitched all around.
These handles turned out looking very nice.
Hope this helps.
Chris