Est. 1998 — 27 years of woodworking knowledge
Rectangular openings?
JL
How do y'all do them?
Typically I rough cut the opening with a "jig" saw after drilling out corner holes.
I then clamp a straight board and use a flush trim router bit on the sides of the opening and a rasp or wood file for the corners.
I was wondering if there was an easier way 
like a drawer in an apron?
Bill Tindall, E.Tn.
I saw the long parts on table saw. Raise blade into the apron and carefully back up a bit as needed, then saw to near end. Finish cut to corner with hand saw. Do vertical cuts with jig saw, hand saw or whatever works for the task.
I like your way but it takes longer.
Rarely...
John in NM
Usually I find a way around the need for them. But I have done it the way you describe and the way Bill describes, and also by ripping two strips, one off each side, then cross cutting to leave the central piece as a drawer front and gluing the other 4 back together around the hole left for the drawer. Can't say as I like any of the methods really, but they all have applications.
Re: Rarely...
Bruce, a MN Galoot
Your method is what I use, too. It makes for a better fit.
Yup, rip and glue up.
Re: Rarely...
John McGaw
I have done it seldom but the only way I know of to get a good grain match between the apron and the drawer front(s) is the slice-and-dice-and-reassemble method. It worked out nicely on the apron of this table which was sliced using a very thin high-tension bandsaw blade to minimize the kerf width.
The picture shows the space between the two drawers on a QS sycamore hall table. The walnut pegs are just for show but everything was so plain I felt that they couldn't hurt.