This style of 'chute is a little more difficult to make than the standard hemispheric, but is such a joy to use, it is well worth the extra time. It is difficult to drop ready opened so recon on making a back pack as well. This pattern is for 12 gores and the normal half section is listed with hem and seam allowance included. If we have got it right you should be able to cut alternate sections up-side-down with no material waste. Use the usual method for assembling and add 4 shrouds on the centre opening spaced at every 3rd gore. 12 shrouds of the same length as the inner are attached round the outside edge and then split the 16 into 2 groups to attach to the back pack. All dimensions are in mm.