In the key of C Major, the Major Second interval would be C to D. Inverting that interval would be D to C. This interval is a minor 7th. Continuing on:

C to E is a Major 3rd
E to C is a minor 6th
C to F is a Perfect 4th
F to C is a Perfect 5th
C to A is a Major 6th
A to C is a minor 3rd.
C to B is a Major7th
B to C is a minor 2nd

When inverting intervals Major intervals invert to minor intervals minor intervals invert to Major intervals. Perfect intervals invert to Perfect intervals (that is why they are perfect). And they always add up to 9.

Play your diatonic intervals then invert each interval for all 12 keys.

Each interval has its own unique sound. Incorporate some intervals to your melody playing or soloing with your teacher during your lessons or playing with your bandmates.

When conducting the student rock bands during the Music Maker School ensembles or summer programs enhancing the guitar lines with some intervals is always a very cool technique.

Best,
Jay