Accidentally ordered the wrong core set... What to do with the extra?

With the two core sets, there isn't really anything that's extra.

• All the ships and pilots are different
• The missions are different
• 6 green and 6 red dice are ideal
• The damage decks are different
• 2 sets of maneuver templates are good when teaching the game
• The asteroids are all different
• Cut down the range template, so you have a range 1, range 2-3, and range 1-3

R2D2 is in original core set.

Sooo OPEN IT!

If you dont use it now, just for R2, extra dice, asteroids..

You will later when you are thoroughly addicted to the game and start playing all kinds of things like Tie Swarm which requires at least 4-5 Tie Fighters (some early incarnations used 7).
Biggs is still a solid ship in any rebel list.
You can even run a Wedge/Wes Janson if you acquire the pilot cards and bases, which are dirt cheap.

All points that mean nothing to you right now, but if you're still playing in 3 or 4 months you will be glad you kept it.

Tie Swarm which requires at least 4-5 Tie Fighters (some early incarnations used 7).

Nononono,

TEH TRUE SWARM is

Cut down the range template, so you have a range 1, range 2-3, and range 1-3

Could you elaborate on this part? It seems counterintuitive to separate the spare range ruler. What benefits do you get from having a range 2-3 ruler?

It helps to have a ruler for checking range 1, deploying ships inside range 1, and ensuring obstacles are spaced range 1 apart. The 2-3 range section is useful for checking if something is inside range 2 and for ensuring obstacles are spaced range 2 from the board edge.

The shorter range rulers do come in handy but I think cutting up a cardboard one may not give you a super accurate measurement. You can buy acrylic ones down the line if you feel you need them in different sizes. Just my opinion.

Two Black Ties are never wasted.

The shorter range rulers do come in handy but I think cutting up a cardboard one may not give you a super accurate measurement. You can buy acrylic ones down the line if you feel you need them in different sizes. Just my opinion.

Yeah, you'd have to be extremely careful and accurate.

We noticed that the cardboard range rulers from our two sets are slightly different - the printing is offset from the cutting for 1-2mm difference. They're probably all slightly inaccurate, so you'd have to find out exactly how long the range is _supposed_ to be, rather than following the printing on the ruler.

...I'm probably a bit pedantic...but this is why I'm preferring the acrylic ones. Also because they're different colours so won't get confused with other rulers, and less likely to be accidentally stolen!