This is blog post about making the 'arena' for the Something Over The Rainbow challenge. The Bill: 9mm MDF 2440mm x 1220mm board - £16.80 Corner Brace 40mm - £7.74 3.5 x 12mm screws - £2.88 Blackboard paint - £5.90 (£11.60 as second coat was needed for removing grey quarter circles) Art Attach PVA glue - kids had grown up sufficiently not to notice half is missing Total: £33.32 (£39.32 - with second coat of paint) Start of the build: [gallery ids="1215,1216" type="rectangular"] Ready for carrying it around: testing-for-transport Checking the size of the arena vs rover: checking-scale Sketching corners: where-are-corners First, live test... live-test ... has successfully passed - with a hamster! {{% media url="https://www.youtube.com/watch?v=Zrdzv22o52c" %}} Priming equipment: priming Painting:   [gallery ids="1206,1205" type="rectangular"] Putting it all together: rover-in-arena-black Question: Grey corners or not? rover-in-arena-corners First test of software coloured balls detection (happy path - almost no cheating): yellow-red-green-spot-on (don't get confused - camera is mounted at 90º CCW) Update: Patience is a virtue... So mere couple of hours all was done: rules-decision So, here we go again - second coat of paint: second-coat-of-paint Grey quarter circles: now you see them - now you don't! And - over the weekend we discovered that screws on the bottom of the arena have bad habit of damaging furniture (i.e. dinning tables). So, here are finishing touches to address it: [gallery ids="1223,1222,1221" type="rectangular"] Next step: coding!