At the moment, Aldi are selling 6 flexible cutting mats for €4.99. They are approx 30.5 x 38 cm, and just the right size to cope with the card from books they also sell at times! I have used many cheap flexible mats for a while with no problem, these are good quality ones.
Now, the question is, how to mark up the grid. In the past, I have done it the hard way, by hand. Duh?
What have I been doing? I'm an idiot! Why didn't I use my Cameo to mark it for me?
This is so easy, you are going to kick yourself if you have not thought of it.
Create a new page and a cutting mat of 12x 24 inches. Put in a page of the same size. I worked out that the grid would fit at 11 x 13 inches. So create an oblong that size and position it at the top left of the mat.
Now for the insides.
Draw one horizontal line of 11 inches and a vertical one of 13.
Use a guideline to position the horizontal one, 1 inch down from the top of your rectangle.
Go to the Duplicate page advanced settings and choose the number of repeats, to go below, select the 'y' axis and put a value of 1 inch in the box, click enter and apply.
You should now have all your horizontal lines done.
Do the same with the vertical ones, placing the line 1 inch in from the left, and duplicating to the right at 1 inch intervals and choosing the 'x' axis.
You should now have your grid!
Now, all you need do, is load your unmarked new mat, without anything on it and use a permanent fine tipped marker pen to draw the lines on it! I used the copy paper setting and 'sketch pen'.
If you are not comfortable with the replicating method, you can simply trace the lines of the cutting mat on screen manually.
TO MAKE YOUR MAT STICKY
I use a temporary spray mount - I think 3M make one but others certainly do - or, if I want a lighter tack, sprays designed for appliqué. That needs applying more often but is good for lighter papers.
If you want, you can use masking tape at the edges to stop them from getting sticky.
NB: Although there is room for another row on the bottom, I have not put it in because the mat would not be gripped by that point to draw it. If needed you can put that bit in by hand later.