I use select model for dynamo as input. Now I always have to select a model. Is there also an option that you don’t have to do that and it still runs the program?
That’s a very broad question and would depend on what you are doing with your script and your model.
Using your example. You are selecting model braces. Are you selecting only one brace out of multiple braces or are you selecting all braces in the model? If selecting one out of multiple, then you have to have some sort of selection method built-in. There are nodes that are made for player that will provide a popup asking the user to make a selection. If you are selecting all braces, you can set your script up to filter to all of the braces automatically (filter element by category and by name). There are packages that have good on screen selection methods like Rhythm and Data-Shapes.
If you get stuck, show your script and describe fully of what you are trying and wanting to do, then we can provide additional quidance.