Ok, a bit of feedback on the tiers for future rounds:
Drop the $1 one, but give access to the mockup with just the $15 tier.
I see myself getting behind all the drives, but only with $15 each time. With the expected 3-5 rounds that will already be a fair chunk. But if you keep shorting the $15 I will never get access to the mockup, though I am actually doing what you said you wanted: Lower donations, but at a regular frequency.
Optimally, with the ammount of funding rounds you seem to be going for, I would prefer a $10 tier "subscription" that gave you access if you donated in all rounds.
Just a thought.