This vehicle includes my previous modifications, so check out my AT-AP Mod and AT-AP Mod v.2 first, if you haven't already done so.
To make the vehicle walk, I first removed the bars preventing movement in critical places. Once the legs could move at all the correct points, I added a small sliding white crossbar on each leg to keep the stationary leg/s stable. Lastly, a transparent bar behind each leg extends to hold up the heavy body when that leg is raised. On a studded baseplate, the model is fully poseable. The walker can stand without the third leg in the pose seen on the set's box, but only with perfect balance.