components used to make a butterworth filter
The wavelength at 1GHz is approximately 20cm (\$v\approx\frac{2}{3}c\$) for electrical signals. In order to be able to use a lumped system, you'll need the physical dimensions of the filter to be (preferably much) smaller than that in order to avoid reflections.

As you'll probably don't want to have any power losses in the passband, I guess you'll be going for an LC ladder filter. Design of such filters is quite heavy on the maths unless you use a tool like (eg. Tony Fisher's LC filter calculator). The inductor and capacitor components (as @Mike mentioned) should be able to handle these high frequencies, meaning that at least the Self-Resonant Frequency (SRF) should be high enough. You will find that this also limits the number of component values that you can use. You can avoid this constraint somewhat by connecting components in parallel/series where applicable.

In general you'll want to go for components with a high Q-factor. There are techniques to compensate for lower Q-factors (predistortion), but I could not find an online tool that implements this.

Design of the filter is usually followed by a sensitivity analysis to find out the allowed tolerance on the component values.