I came across a blog post which I thought was interesting and I thought I would give it a go.
In the article above they use a Ribba box frame from Ikea, I found something suitable in a local branch of The Range, it was about £4 and is a little shallower than the Ikea frame. A visit to Hobbycraft found me a self adhesive felt sheet, I choose green but they had plenty of colours to choose from.
The back of the frame had the folding stand up bit, I broke that off, pulled the backing paper from the felt and stuck it to the front of the back panel. Take care pulling out the glass, mine broke, dispose off properly, pull out the little metal tags that hold in the glass. Put it together and job done.
The bottom did have a couple of rough places on it, I decided to add some sticky foam pads, sold to go on furniture legs to stop them scratching the floor, this raises it off the table.
In all a quick project, just took minutes and cost about £5 to make but a great addition to the gaming collection.