While it is not in St Louis, K-10 Model Trains in Maryville IL is great! It is apx 16 miles from down town St Louis Mo.
https://www.k-10smodeltrains.com/
I am lucky, only 2 miles from my house!
Cuda Ken
I hate Rust
Good luck. I drove through St. Louis about a year ago and could not find one.
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Hopefully someone chimes in to help out. I am going back through St. Louis in February.
-Kevin
Living the dream.
What hobbie shop is a good one in St Louis Mo?