Sanding block for 115 mm roll paper finger saving

We needed to sand up to the edges and corners on a large surface where the big power sander would not reach, so I designed this sand block. I looked at what was already available, however though there are some good designs, none quite fitted my needs on testing them. These are the criteria this model had to meet.

• Must fit 115 mm roll sandpaper
• Has to be easy to fit the sandpaper
• Must be comfortable to grip without touching the sandpaper or hitting fingers on adjacent surfaces
• Any fixings must be strong with no fine threads. The screw has a 2mm pitch and has a cylindrical core to add extra wall strength. 
• Must print reliably with a 0.2 mm standard print profile. I've increased the walls to 4 and use gyroid infil, but other than that it's pretty standard.
• Should not need supports (I hate having to fiddle around with supports)

This is what I came up with, I hope you find it useful too.