Something homemade by S. Circus tickets to me sound presumptuous and a little controlling, and at a year and a half not necessarily what your S would most want to do. You take him to the circus if you think he'll like it, don't send your H to do it with tickets you gave him. Just my two cents.
I did lots of Best Dad Hands Down t-shirts with painted on kids' handprints over the years. At 17 months those hands are so tiny and cute! Or fingerpaint a page of handprints and frame it like a poster. I used to squirt a bunch of primary colors on one dish so the handprints would be all multicolored and it actually made nice frameable art. Or go to a pottery place if you have them and do thumb prints all over a dish or pencil holder to make it polka dotted with S's print. Or a cute photo of S framed, or better yet if you have one of just S and dad. But I like the handprints better because they are as close as you get to the gift really being FROM S.
Adinva 51, S20, S18 M24 total 6/15/11-12/1/12 From IDLY to H moving out 9/15/15-3/7/17 From negotiating SA to final D at age 50 5/8/17-now: New relationship with an old friend __ Happiness is a warm puppy.