No one says you have to pull off a Martha for Halloween. (Yet you insist.) Then again, no one knows that your famous cupcakes hail from Costco and that you hem pants with a stapler.Keep things easy breezy with a DIY animal costume kit from local crafter Cassie Divine. Pitch in a pint-size sweat suit and fifteen minutes to two hours of your time — depending on the creature — and Divine will provide presewn felt add-ons, needle, thread, and instructional YouTube links.Options range from the familiar (dog, cat, bunny) to the unexpected (turtle, koala) to the extinct (dino). And your tyke’s finished getup promises to rake in both smiles and sugar spoils. Divine even adds some extra sweetness by donating 10 percent of profits to the World Wildlife Fund.Trick and treat.Available online at etsy.com.Photo: Courtesy of DIY CostumesPERUSEPreschool Gallery HourWhat: A free monthly visiting hour customized for wee gallery-goers with movement classes, performances, and art projects.Why: Sendak’s in the house.When: Sun., 10 a.m. (Plus all second Suns. thru Nov. 8.)Where: San Francisco Contemporary Jewish Museum, 736 Mission St., b/t Third & Fourth Sts. (415-655-7800).ENTERTAINMill Valley Children’s FilmFest Opening PartyWhat: Mini cinephiles screen kid flicks from Northern Europe before partaking in after-party festivities like face painting, gourmet finger-food, and additional flicks.Why: They like to watch.When: Sun., 12:30 p.m. Where: 142 Throckmorton Theatre, 142 Throckmorton Ave., at Bayview Ave., Mill Valley (415-874-6833). Tix $5 with code PARTY11.BUYBabyLegs Sock Gift BoxesWhat: Sweetly wrapped gripper socks come in color-coordinated sets of six for mixing and matching.Why: Sock it to ’em.When: He kicked one off — three blocks back.Where: Aldea Ninos, 3338 17th St., b/t Valencia & Mission. (415-865-9807).