I forgot what a pain intarsia is, especially with 5 colors… I started using bobbins but quickly abandoned that and used whole skeins (stuffed in socks).

I added the seed stitch border in white AFTER completing the color blocks. The pickup round was all stockinette. At the corners, I did a KFB/KFB every other row to sort of square off. It’s not a perfect miter but looks good in seed stitch.

My adult nephew is still Lego-obsessed and builds huge complex things. The baby is a girl but it’s too cute, will work for either gender.