If anyone fairly new to the hobby isn't familiar with the Iron Trap Garage youtube videos hosted by a gentleman named Matt (Murray I think), here is a good place to start.  In this video Matt shows how to form a sub frame on a model 'A'.  Matt is also in a lot of 'Eastwood' videos on youtube and that was how I got my start in 2017.  I didn't have a clue where to begin on a rolling chassis but Matt's 'Eastwood' videos were a blessing to me so I bet these Iron Trap Garage videos are a big help as well for anyone anxious to learn more.  I could be wrong of course but with all the 'how to' videos on the net, you want to find one where the guy is clear and succinct and knows his stuff.  Check them out:  https://www.youtube.com/watch?v=0-MlDRlNcEU   Good luck !