Are you trying to keep them organized? 3000 of those pieces are fairly small (in the lego world). I use these style Iris locking bins I got from Costco. Come in a 4 pack, 12 qt size I think for $15. So larger and cheaper than shown below.
https://www.amazon.com/dp/B00CQGTH00/ref=cm_sw_r_cp_apa_fabc_X1WBJVHPPVRKJ8VCHNBY
If you want them to travel safe and keep some basic organization, these storage bins from Harbor Freight are good as well.
https://www.harborfreight.com/20-bin-medium-portable-parts-storage-case-93928.html
I use both, and they take a fair beating before spilling open.
Are you trying to keep them organized?
Yes, while at the same time prepping them up for travel as I might move away in the near future. Trying to shoot two birds with one stone here.
3000 of those pieces are fairly small (in the lego world)
Yeah but once I underestimated them too much and bought a smaller Akro-Mil ripoff 3x3 cabinet lol. Probably got ripped off too since it's about as tall, deep, and wide as the length of a sizeable gaming mouse. Can't even fit 2 mechs' worth of parts. The cockpits and other larger pieces had to stay in the boxes they came with, lol.
I've gone a bit overboard and ordered more parts and sets and now I can't fathom how large a storage I'll need. I counted my orders' pieces and got up to that estimate with a bit of a wiggle room.
https://www.amazon.com/dp/B00CQGTH00/ref=cm_sw_r_cp_apa_fabc_X1WBJVHPPVRKJ8VCHNBY
How large do you think I'll need to go? I'm thinking one 5-6 liters box would do..
https://www.harborfreight.com/20-bin-medium-portable-parts-storage-case-93928.html
How large are each compartments? I can't find these from local sellers, might as well try to find something else with similarly sized compartments..