Here I've glued the inside top to the outside top piece. I've overlapped the finished edge of the inner crown piece over the unfinished end and glued. Little clips are handy.
Wrong sides together sew a lining to the outside edge of the interfaced brim piece. Notch the edge, turn and press. Open it out and sew the center back seam. Press this seam open. (Sorry I didn't get a picture of that.)
The only thing left to do is glue the outer crown in place overlapping the finished edge over the raw edge and have fun decorating your hat.
Somewhere I saved a PDF of my hat pattern with three different brims but it seems to be hiding on my computer. In the meantime, Missy's Imaginings has transposed a people pattern into doll sizes that should work for this technique. You would need to use the pieces labeled for buckram for your interfacing pieces. I would double check that those pieces fit well together and remember to make your outer crown piece about 1/4" longer. https://missysimaginingsdotcom.files.wordpress.com/2020/12/hats-for-bjds.pdf
Have a great holiday weekend.