Making a Box Cushion the Easy Way

I've put this project off for ages and I've spent so much time procrastinating.  How am I going to cover this square sponge foam? It's for the girls, so the older one can sit at the table at her place. Of course I volunteered to sew and cover it, I'm the sewer in the family...Then I panicked and thought 'how am I going to do this with oilcloth?'....I've never made a square box cushion cover with oilcloth before and I knew it was going to be a tricky sew....

Fabric: About 1/2 metre of Oilcloth

In the end I chose this tutorial to follow: Floor Cushions

Other Box Cushion Tutorials (I considered):
Square Tufted Floor Pillows
Perfectly Portable Cushion
Boxed Cushion Sewing
Patchwork Floor Pillow

I thought I had this sussed! I wound a rubber band
around my Bernina 801 machine foot so the
glue would  really stick. UHU glue fixes
 everything right? No it doesn't, the plastic
 was still lifting!

Finally I finished it...What an effort!
I'm thankful I made the easier version. Never
again will I try this with oil cloth...

'Trouble is a friend! He was a total nuisance, he ate the
 Dacron stuffing, he knocked over my sewing box
and started eating the sewing machine chord..and
 out of spite he then sunk his sharp teeth into my
oil cloth sewing box.  Now it has two puncture
holes :(