Help!!! How to sew box corners!
I hope I can describe this problem right...my sister and I are sewing an isolette cover for the NICU Flight Unit made out of PUL fabric. So, we've got the measurements and my sister pinned it using the actual isolette. The question is: when sewing the seams, how do I stitch the corners when the side piece corners are to be left open for access????? We know what the corner should look like because we've pinned it but when actually stitching the seams, we are very confused! LOL The cover is just like an upside box (without a lid of course) with the corners not stitched. I know there is a simple method but for the life of us, we can't figure it out. We've both been sewing most of our lives!
I know this is a geometry problem which we cannot solve!! Help!!!!!!