It is useful having a pen available in the kitchen and, for quite a while, I’ve been keeping a biro on the fridge using a magnet held on with an elastic band wrapped round several times. It has been a good solution but the elastic band is now perishing and it was time to work out what to do next. I suppose the simple solution would have been another elastic band or perhaps a dab of hot glue but I’ve got a 3D printer so today I’ve been designing, prototyping and printing a custom solution.
I observed that this particular biro has a screw cap at the end opposite the writing point. I realised that, if this was unscrewed a bit it would still be firm but could also hold a ring in place which, in turn, could hold a small fitting to house the magnet.
Draft one came together quickly but a couple of the measurements weren’t quite right. In particular, I’d neglected to leave enough depth for the magnet so the housing wasn’t flush to the barrel but bent away from it. I ended up doing three more prints, with tweaks between each. The first was a partial print to check the lower section with the ring and housing. Next I realised that rather than a weak ring, I could use a rounded triangular shape (actually a hull between a circle and a rounded rectangle) to add more strength. The dimensions were still a bit off but my final version solved that as well as adding an extra hole to make it easier if I want to push the magnet out in future: it was pressed in tightly and a bit of a pain to extract from failed prototypes.
The pen now sits back on the fridge looking neater than it ever has before and, meanwhile, I am starting work on the next design project…
