Hi, why don't you consider to iterate feature classes instead of use multiple inputs?
You can write every partial result in a scratch GDB and then append all to a new fc.
Nobody knows how? I'm desperate... 😞
Put all of the outputs of the buffer into the Merge tool, then the Dissolve tool if you want the buffers to become one giant feature.
Also, are you sure you want to use Select? Are you using Coverages or shapefiles/geodatabases? Probably you really want to first create an empty polygon feature class with the correct Spatial Reference and output fields you will want to Dissolve your buffers on. Then make a model that Iterates Feature Classes (shapefiles) in a directory (See also this link) outputting the feature class to the Make Feature Layer tool, then the Select Layer By Attributes tool, then the Buffer tool, then the Append tool to the empty feature class with the No Test option to fill it with all of the buffers. You should set the overwrite outputs environment option to permit overwriting so that the Buffer tool overwrites its output with each iteration. Don't worry, the Append will save the buffer results before the file is overwritten by the next iteration. Then in another model input the prior model's Appended polygon output feature class into the Dissolve tool using a nested model approach to create a single giant feature from all of the buffers (if that is what you want).
A final alternative approach is to do no selection of the original shapefiles initially and just input all of them to the Merge tool to create a single feature class (assuming all of the inputs are based on the same geometry), then use the Merge output with the Make Feature Layer tool, then the Select Layer by Attribute tool, and finally the Buffer tool with the Dissolve Type All option set (if you do not want to preserve attributes) or List Option if separate shapes are to be preserved based on an attribute that should not combine. This approach avoids the need for the Dissolve tool.
Thanks for your reply.
Te input features can be lines or point, not are based on the same geometry....
If I put de multi-outputs buffer on Merge tool, the output is multiple too...
I use Select tool because I need execute a filter (passed by the user) over the layer (passed by the user too), then create a buffer of selected elements