Another female gadget lover here... already married (er, and old enough to be your mother), but there's hope! (I covet both Cricut
and computerized routers, and subscribe to both MAKE and CRAFT magazines.)
I have a separate bank account with debit card for hobbies, including gadgets. I have an automatic deduction from my regular paycheck, and if I take an extra part-time job, I can put that money in there, too. I only buy fun stuff from this account (meaning that I don't buy fun stuff from our other bank account or using a credit card, not that I never buy food from this account, though it tends to be "fun food").
The inverse method might work better for you: crank up your 401(k) contributions, etc., and set up a separate savings account with your bank with an automatic payment each month. Whatever is leftover after that and the bills is good for whatever you want to spend it on.
In the past I've also had a mandatory waiting period for items depending on the price, e.g. I can spend up to $10 on impulse, but $10-100 requires three days "cool off" time, over $100 requires two weeks, etc. The amount of hold time depends on my current discretionary income, of course. Now that I have the fixed budget, I don't worry so much about this.