 Here is the Python code using the pyaedt library that performs the tasks as described:

```python
import os
import shutil
import pyaedt as ae

# Create a temporary folder and print its path
temp_folder = os.path.join(os.getcwd(), 'temp_folder')
os.makedirs(temp_folder, exist_ok=True)
print(temp_folder)

# Download an example file into the temporary folder
ae.check_and_download_file('example.prj', os.path.join(temp_folder, 'example.prj'))

# Set non-graphical mode and launch AEDT in graphical mode using SI units
ae.set_non_graphical_mode(False)
ae.set_units('SI')
ae.launch_aedt()

# Initialize AEDT and launch HFSS 3D Layout
ae.initialize()
ae.launch_hfss_3d_layout()

# If the AEDT file already exists, it removes it and saves the project in the temporary folder
if ae.validate_file_exists_and_pyaedt_tabs_added('example.prj'):
    ae.clean_cache_and_files()
    ae.save_project(os.path.join(temp_folder, 'example.prj'))

# Print the boundaries from the setups object
print(ae.get_boundaries())

# Hide all nets and then make only two specified nets visible
ae.find_and_fix_disjoint_nets()
ae.hide_all_nets()
ae.make_net_visible('Net1')
ae.make_net_visible('Net2')

# Plot the two specified nets
ae.plot_nets(['Net1', 'Net2'])

# Make all layers visible
ae.all_layers.set_visible(True)

# Change the color of a specified layer
ae.all_layers['Layer1'].set_color('Red')

# Disable the visibility of components for the top and bottom layers
ae.all_layers['Top Layer'].set_visible(False)
ae.all_layers['Bottom Layer'].set_visible(False)

# Fit all so that all can be visualized
ae.fit_all()

# Close the project and release the desktop
ae.close_project()
ae.release_desktop()
```

Please note that you need to replace 'Net1', 'Net2', and 'Layer1' with the actual net and layer names you want to work with. Also, make sure to install the pyaedt library before running the code.

You can install the pyaedt library using:

```
pip install pyaedt
```