I made a studless Technic to SG90 mini-servo adapter. These things are $18/10 on Amazon right now. I'm going to build a hexapod. Link to STEP and STL files in comments. :
Amazon.com: Seamuing 6Pcs MG90S Micro Servo 9G Servo Motor Metal Geared Micro Servo Motor 9G Smart Robot Car Helicopter Plane Boat : Toys & Games
Buy 4pcs High Speed SG90 MG90S Digital Servo Motor RC Helicopter Airplane Boat Small Robots Servo Airpl at affordable prices — free shipping, real reviews with photos — Joom
Permanent Magnet Motors Electric Motors Mophorn Nema34 12Nm Closed Loop Stepper Servo Motor 2 Phase Hybrid Driver CNC Kit sanjoaquinrtd.com
Metal Rotating One way Steering Valve WA 470 Servo Steering Gear Model Accessories Including Servo Motor|Parts & Accessories| - AliExpress
2 Sets 20KG Digital Servo, DS3218MG RC Servo Motor High Torque Servo Metal Gear Waterproof Servo for RC RC Model DIY (Control Angle 270°) – Dorothy Store | Beauty Products
These are the hottest toys of 2021, according to Amazon. And a bunch are on sale now - CBS News