For the gowns I ended up using this pattern and tutorial. I upcycled clothes as well, making these gowns basically free to make. I even was able to re-purpose elastic so I didn't have to pay for anything other than thread. For a few of the gowns I re-purposed very soft sweaters instead of t-shirts, and I thought that worked well also. I didn't put elastic in the bottom of the sweater type gowns, but simply used the bottom hem of the sweater that was already more tightly woven and stretchy.
Instead of using designs already on t-shirts, I chose to applique and embroider them. This took longer for sure, but I was able to make very custom baby clothing this way. And I think they turned out really cute. I think these could also make really great baby shower gifts.
For the onesies, I could find a 0-3 month pattern on the internet, so I ended up simply folding the gown pattern into a onesie pattern. Probably tracing an existing 0-3 onesie would be even easier, but I didn't have any in that size here. I sewed the onesies together in similar fashion to the gowns, just finishing the contoured bottom with a tiny rolled hem all around and adding snaps. After I had sewed a bunch of onesies, I embroidered and appliqued these as well.
|Gown pattern folded into a onesie pattern|