If you’re a holographer and you’re like me, you use your developer for as long as you can before throwing it out.
Some people will preserve their developer by floating another tray on top of it but that’s never appealed to me because it’s messy and I would need a place for the "lid" to sit and drip while I’m actively using the developer.
Start off by cutting the last half inch off the rubber stopper. Scissors work fine for this.
Now you’ll need to cut a proper sized hole in the Biokip lid. The easiest way I found was to put the rubber stopper on top of the lid and trace around it using a sharpie. Now take a soldering iron and burn your way around the inside of the circle you just made. Start off my pushing the iron tip through the lid and make a ring of holes. Now pull the soldering iron around the circle until the plastic disk drops out.
You may be thinking that you’ll be generating a lot of smoke and smell at this point but surprisingly the plastic is a lot more like hot glue than most other plastics I’ve melted and you’ll find that these melt easily but don’t smoke much at all.
Once you’ve got the rough circle made, test the fit of the stopper. Keep widening the hole until it’s just wide enough that you can push the stopper through. You want there to be some resistance.
Now take a hobby knife and clean up the edges of the hole.
Now for some more fun. It’s time to play with adhesive. I used a garden variety RCV I bought at the hardware store and sealed the edges on the top
and bottom of the stopper
Now let the RCV cure for 24 hours.
Once that’s done you can put the top on as normal and then use the pump to suck most of the air out.
You’ll find that the end clamps will pop off due to the deformation of the top and bottom of the container but the container will remain air-tight.