Trying to model a waiter carrying a drinks tray as he walks. How do I get his hand to stay (relatively) still as he walks, and keep the same hand pose for every frame?

Try this: 1. Use the Walk designer to move the waiter. 2. Independently, move the tray itself so that it stays relatively steady in front of the waiter. (Just move it along the path, setting only a few actual frames and letting the spline smooth it out.) 3. Turn off IK on the relevant arm. 4. Go to frame 1, pose the arm and hand to hold the tray. 5. Clear all the keyframes (which were supplied by the WD) for the entire arm. In the keyframe graph, draw a rectangle around all the arm parts, and extend it through all the frames you want to clear. Hit the Minus button in upper right, then close the keyframe graph. 6. Turn on IK for the arm. 7. Parent the hand to the tray. (Tray is parent, hand is child.) The hand and arm will now bend appropriately to keep the tray in place. 8. Make fine adjustments in the tray so that it bounces just a bit.

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Thanks so much for your advice, it's all clear to me now.