While holding right click to block with a shield in your off hand
If the shield ducks down you will "right click" allowing you to enter chest or dispensers. after you exit them your shield will always be in "block" mode allowing you to right click with tools and other items, except without the movement speed reduction, until you right click again.
Environment
Model Identifier: MacBookPro11,1
Processor Name: Intel Core i5
Processor Speed: 2.4 GHz
Number of Processors: 1
Total Number of Cores: 2
L2 Cache (per Core): 256 KB
L3 Cache: 3 MB
Memory: 8 GB
Dupe of MC-86252