Pegboard Jig

This is NOT my design. I found this on Instructables, it was created by a user named Paige Russel. It was uploaded there for users to download for free and either print themselves or have an online printing service print for them. I have found one thing that does need to be altered in this design, but I do not know how to do it. The peg wings on the outside edges of the jig need to have the holes on the underside increased to 1/4 inch or .25 inches in order for standard 1/4 inch dowel pins to be used. There are 4 pegs included in the STL that get installed into those holes, that are not a very good fit, and I have actually destroyed mine. I had an online printing service make this for me as I do not yet own a printer, I am still saving up my money to buy one. I am hoping that someone out there can make the alterations to this that I am looking for. My only other option would be to bore out the holes with a 1/4 inch drill bit, but I am afraid that I will either break the jig itself whil