This is a linkpost for https://alexhollow.wordpress.com/2021/09/11/pack-a-travel-bathroom-bag/
Huh, I realized I am already doing this halfway -- there are things I have many copies of (toothbrush, toothpaste) and I keep a copy in a bag (actually a box, nevermind), and there are things that I add there before travel and remove them afterwards, because I don't keep extra copies of them... and $30 could complete the bag.
As Gareth mentioned, checklists are great for things that are large, expensive, or expire quickly, so you don't want to keep an extra copy of them in a bag. Things like shampoo, you can pour them into smaller bottles.
Brainstorming time: what else is small, inexpensive, doesn't expire, and is useful when traveling? For example, pen and paper, playing cards...
Or just put a checklist in your travel bag. I recommend the small refillable bottles that you can get at places like muji (no idea if muji is a thing where you are) as they mean I can just take enough for a weekend or one week , keep volume to a minimum and allow me to take my bag as carry-on. Having spares is a great reason to do this though.
About a year ago, I realized that packing all my bathroom stuff was one of the more difficult and annoying and error-prone parts of packing for travel. So, without planning on going anywhere, I packed my travel bathroom bag.
This bag had all the things I was previously likely to forget – toothbrush and toothpaste, floss, comb, hair product, deodorant, nail clippers, travel-sized face wash and moisturizer. That’s a lot of stuff, and most of it I could do without. But why risk it? I’d rather be able to grab a bag and know I have everything.
Put together, the bag probably cost around $50. The time savings while packing probably make it worthwhile by itself, but also I will never forget any of those things ever again on any trip. Overall, it seems like a win!
An ancillary benefit of this bag is always having backups of everything. If I run out of toothpaste, or floss, or hair product, I have a small backup supply of everything that I consider useful enough to go in the travel bag.