Getting the runners sliding well and tight side to side is the hardest part of building sleds. I have used wood and cutting board material (HDPE??) prior to this sled. Wood gets loose, swells due to humidity, HDPE swells at the attachment screws and makes for a lot of trimming the width to make the sled push smoothly. If these aluminum runners don't have issues will use them on future sleds.
The sled I made last year has walnut runners and now is loose. Got some HDPE strips already cut for it. It may wait till next fall.