Use your tablet device to measure out a template on your greaseproof paper. Draw around the device with a pencil & ruler, giving approx 1.5cm extra around all the edges for the seam allowance. Create one simple rectangle for the front piece, and the other should extend longer with a slant to create the flap.
Pin the greaseproof paper templates to your fabric and cut out. Do one of each on your patterned fabric, plain fabric and the wadding.
Next, take your plain fabric and using your dressmaker’s pencil and a ruler, draw out a criss cross pattern, with approx 2cm gaps between the lines.
Place your patterned fabric face down, place its matching piece of wadding on top and finally the matching piece of plain fabric with your criss-cross pattern facing up. Do this for both the front and back panels, and pin the three layers together to hold in place.
On your sewing machine, use a simple straight stitch setting, to follow the criss-cross pattern to create the quilted effect. On the back panel, do not stitch right to the edge of the slanted edge, leave approx 0.5cm unstitched.
Take your back panel (the one with the slanted flap) and fold in the plain fabric & pin.
Trim off the excess wadding. Remove the pins, and then fold in the patterned fabric too, to create a hem along this edge. Stitch this across on your sewing machine. You will also need to hem the longest side of the slant. And on your front piece, you will need to create a hem for the top edge. (where you device will slide in.)
Place your front and back pieces patterned sides facing together, pin and then tack to hold in place, before stitching around the two long sides, and the bottom, on your machine. Perhaps change your machine setting to triple stitch for extra strength here.
Turn out your case the right way round, and finally cut a strip of Velcro to fit and stitch this on the inside of the flap and the front panel to close your case.
You could also add extra embellishments such as trim or ribbon along the edge of the flap or perhaps some pretty buttons for extra interest, it’s up to you!