you may want to consider an erector set. a great toy from the 70s still made of metal .... amazon or walmart ... https://www.amazon.com/Meccano-Construction-Motorized-Building-Education/dp/B000GOF5S2/ref=sr_1_5?dchild=1&gclid=CjwKCAiAhbeCBhBcEiwAkv2cY2jmzJ1S4-dYtF7eE0y4YhWeQX1pzwzga-CBGkSyLSU1B-CAw0ppnxoCWO0QAvD_BwE&hvadid=178128893184&hvdev=c&hvlocphy=9028903&hvnetw=g&hvqmt=e&hvrand=7797696493070111749&hvtargid=kwd-15040490&hydadcr=2989_9918870&keywords=erector+set&qid=1615741984&sr=8-5