Unless you plan to watch your money like a hawk, there's not much you can do for 3 years, find a bank/credit union CD with a maturity of 3 years or less, look at some TIPS since we're in inflationary times.

Why are you not invested in the military TSP?

Why are you not invested in a Roth IRA?

You are missing out on some great oportunities.

Do some research on saving and investing.

Invest it. CD or lend it to someone who you know will return the money with interest.

I am in the military and have saved up $10,000 so far. I am getting out of the military in 3 years and I plan on using my money towards a large purchase (small house or car). I am going to continue to save, but what should I do with $10,000 now? I want to be able to access this money in 3-4 years.