This relates to a world in which there is no magic and only medieval technology. The ruling and religious classes want to convince the general populace that magic exists.
For example a sword-smith has been tasked with making a 'magical' sword that can only be drawn by 'the chosen one'.
Of course there is to be a secret mechanism that only those in the know can operate.
The sword has to be a top quality sword that is forged by standard methods before inserting in the stone.
The stone has to be real stone. It can be shaped using medieval tools but should be heavy enough so that it can't easily be moved. The sword must fit snugly.
The mechanism for releasing the sword must be very difficult to discover. Nothing so obvious as pressing a simple foot pedal.
A circle of six-foot radius is marked on the floor around the stone. Only one person is allowed in the circle at a time.
There are guards to prevent damage to the stone or sword but anyone whether commoner or not must be allowed to try. They can examine the sword and the stone carefully before trying, and they have three attempts each. The guards will only intervene to prevent damage or more than one person at once entering the circle.
The chosen one should not be allowed to try too soon. There must be many failures first to 'prove' it is magic.
How can a sword-smith use medieval technology to simulate a magical sword in the stone that can only be released (or put back) by someone who knows the secret? No actual magic is allowed.
There is some flexibility about the locale and the shape of the sword. I imagined something like the following but if it invalidates an existing answer I won't make the picture a factor when choosing. Add armed guards and possibly a large pavilion-tent to protect from the weather.