Well not all the framing I do requires me to cut mats.  I also find that using alreay made mats can save a lot of time and make the project really stand out.  Below is a set I made using the 12 Filmstrip pins from WDW.
I started out with a mat that is used for school pictures.  It is a double mat.  The White you see here and the gold back on the mat below.
I filled the center hole with a picture I got of the web.  I thought it captured what I was going for.  I then taped it to the back of the gold mat.
After I have done that I then layout the pins on a piece of uncut mating board.  This will act as the backer as well for the whole set.
I would like to point out that while I'm showing the pin backs here.  It is best to use a rubber back as they will not mess up the wall.  I will be changing these.. 
I then start the layering of the mats.  If you look you will see that Not all the pins fit perfect in the cut outs.  This is one of the draw backs of pre cut mats.  I don't think it hurts the over all effect.
I then add the outside mat and add it.  I could have just not used the gold  to make the pins fit in the cut outs perfect but I like the look the gold gives
And this is the final step...  Finding a frame tat goes with what you imagined.  Hope this helps out.
Please email me if you have any questions.
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