Owning several Gumotex IKs with the rubbish footrest pillow (left), I came up with my footrest tube idea years ago. It’s since been copied (or maybe just implemented) by many manufacturers.
In a kayak, a footrest isn’t something you rest your feet on while watching Netflix. You lightly brace against to stop you sliding down in the seat and to improve you’re connection with the boat. To that end it wants to be solid, not mushy.
I was never really that happy with my Seawave’s drainpipe arrangement: an adjustable strap running forward from the seat and a counter-tensioning elastic pulling from the bow to keep the tube in position. Too many straps, with entrapment and aesthetic issues. All I really needed to do was glue on a couple of D-rings either side of the footrest, but I like the idea of reversible (non-permanent) modifications.
Then I remembered a clever idea someone passed on to me: straps threaded through a small piece of plastic pipe. You can buy them ready-made to jam into car doors to lash stuff down. As was suggested, these anchor straps could also jam into the cavity/channel (left) you find on most tubed and even FD-S IKs with removable floors, where the floor meets the sides to make repositionable/removable lashing points. Also, they are dead easy to make.
As footrest tube strap anchor points they work especially well because the tension on the strap is sideways (towards the bow) for better jamming, and they can be slid forward along the channel when paddling two-up and beyond the adjustability of the strap. And best of all, no tedious 2-part D-ring gluing required.