Painters,
Here is the link I mentioned for stretcher bars; they come in sets of two. Remember you will need two 18" and two 24". If those exact dimensions are not available, get as close as you can. Good luck!
https://www.amazon.com/Masterpiece-Standard-Canvas-Stretcher-Strips/dp/B000AMYJS2/ref=pd_sim_201_2?_encoding=UTF8&pd_rd_i=B000AMYJS2&pd_rd_r=WPNSM4B8FN11JDB6MBCQ&pd_rd_w=9Wxyu&pd_rd_wg=O6fzW&psc=1&refRID=WPNSM4B8FN11JDB6MBCQ
