You can still buy buckets/toolboxes of assorted Meccano. They come with plans for things which you can happily ignore.

https://www.amazon.com/Meccano-Junior-100-Piece-Bucket/dp/B0...

https://www.amazon.com/Meccano-20070926-Junior-Bucket-150-Pi...

https://www.amazon.com/Erector-Advanced-Toolbox-Construction...

https://www.amazon.com/Meccano-6024795-Meccano-Erector-Advan...

(Results of a quick Amazon search. I'm sure there are more.)