When I was looking for a wedding dress, I went through... unconventional sources. As long as it was white, pretty, and didn't have a train (I'm incurably prone to tripping), I didn't really care whether it was technically considered a "wedding dress" or not. From what I could tell, the main difference between a "wedding dress" without a train and a "pretty white dress" was hundreds of dollars in price! I found one that I really liked from Holy Clothing and had it shipped.
Their clothing ships directly from their factory in India, and I'd procrastinated a bit on placing my order, so I was starting to worry that it wouldn't arrive in time when it finally showed up. Unfortunately, the embroidery along the edge of one of the sleeves had snagged and was unraveling! They have an excellent customer service department, and when I sent them a photo of the damage they immediately refunded my order and told me to just keep the dress.
I wasn't willing to risk the delay of ordering another dress from India, though, and went with a dress from a US company (The Rose Dress, which I highly recommend!). It arrived just in time and fit perfectly, so the first dress was relegated to a shelf in my sister's closet and forgotten about... until now.
How crazy would it be for me to try to use the yardage from the first dress to make a baptismal gown? It is a floor-length dress, so there is certainly more than enough material... and the whole thing is hand-embroidered, so it would be lovely... if I could do it. I don't currently have a pattern, and would want to find one that someone else can attest really works. It would be so nice to make a baptismal gown to use for all of our children, though!
I haven't been able to find specific guidelines for the design and composition of baptismal gowns for Catholics, and the incredible variety of styles and materials available for sale across the Internet seem to indicate that a baptismal gown isn't subject to the same sort of regulations as some other liturgical garments (natural fibers, etc). As far as I can tell, the most important thing is that the garment be white, symbolizing the fullness of Divine Grace with which Adam and Eve were clothed in the Garden of Eden before the Fall, and the purity which is restored to the child's soul when original sin is washed away in Baptism.