3 x 1U and 2 x 1.25U Ctrl Silicone Keycap Molds [MX Compatible Switches] : ID 5079 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Windfall Keycap Molds Silicone kit, Handmade Crystal Resin Molds for Key Caps of Gaming Keyboards Mechanical DIY Cute Cat Claw, Tab, Keycap Silicone Mold and Key Puller - Walmart.com
Akko ACR Pro 75 + Gateron North Pole V1 + CIY Nogi Silicone Keycaps (sound test in comments) : r/BudgetKeebs
Amazon.com: SKYLOONG Silicone PBT Mechanical Keyboard Keycaps 140 Keys Full Set G2 Profile with Keycaps Puller Keycaps Compatible GK61/64/68/75/84/87/96/98/104/108/Key(Pink) : Video Games
Amazon.com: Upgraded Novelty Cat Claw Palm Cat Paw Keycap Silicone ABS OEM Profile ESC Arrow Artisan Key Cap for All MX Switch Gaming Mechanical Keyboards (Zebra) : Electronics