After years of failure, I found the best and most efficient was to glue this

https://www.amazon.com/gp/product/B00M1UAF6G/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

into the bottom of this

https://www.amazon.com/Really-Useful-Box-1-75-Litre/dp/B004VRBVGU/ref=rvi_48/147-0611595-2455456?pd_rd_w=Yf7hI&pf_rd_p=c0296674-5a83-4ad6-b035-0702d2b359df&pf_rd_r=PE434CDGJW78YQV2YYXS&pd_rd_r=6a8ed253-0e6d-4be8-8b6a-25a29ba19bd0&pd_rd_wg=mdgVc&pd_rd_i=B004VRBVGU&psc=1

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then put these

https://www.amazon.com/Tiny-Round-Disc-Magnets-3x1mm/dp/B08XLSRHQN/ref=sr_1_9?dchild=1&keywords=miniature+wargaming+magnets&qid=1628799198&sr=8-9

On the bases of the models. It stucks well but not so well that you have to rip them off the magnet sheets. The boxes stack well without wasted space.

This is the kind of thing you'll need to look for then. Hope that helps!