You can make your own composite beam/load bearing beam by ripping down plywood sheets and gluing the pieces together with wood glue to make a long thick beam. Look them up, the strength and yield limits on them is off the chain. Made a 12 footer out of 2 sheets of I think 3/4 inch plywood to tear out a wall about 15 years ago and it has not given 1/4 of an inch. You can also have them made for you.
Couple of issues with this. First, don't do it IF you are doing anything that needs to be blessed by an inspector. There are too many variables to determine if the finished product is going to be acceptable, or a failure. Plywood selection, grade, fasteners, fastener schedule, adhesive selection and more can affect the strength of the finished product. Field applied glues and construction adhesives are not factored in by most codes, since there is little control over their application. For example, I could use a decent wood glue to build a beam, and properly clamp and cure the joints under ideal conditions ( temp. humidity, clamp pressure, cleanliness, volume and application of adhesive, etc....) and end up with a great product. The framer down the street could use the same glue, in near freezing conditions, on dirty lumber, and shoot the entire assembly together with undersized air nails. His work is useless, mine is rock solid, and nobody can visually determine what is what.
The other issue is that a lot has changed in modern construction. Laminated veneer lumber (LVL) is now common on most construction sites. LVL is essentially a plywood beam like you made yourself. It has a few big differences, including the fact that all the veneers orient with the length of the beam, which is opposite of plywood, where alternate layers are rotated 90*. It is also built under much tighter specifications than any field made beam could be. It is incredibly strong, and has greatly reduced the use of steel beams and glu-lam beams, particularly if the glu-lam is structural and not a "show" beam, exposed in the final product. Finally, the stuff has become such a commodity that it's pretty cheap. One way of looking at it is that LVL is roughly 3X as strong as the piece of lumber it replaces, such as a 2x10 or 2x12, and it's rough 3x the cost of the piece of lumber. bottom line, I'm an old timer, and I've built plywood beams, and other built up structural beams. They can work well, but now LVL is faster, cheaper, easier to use, and incredibly strong.