I made a see-through challenge toy this time, with a marble, jingley ball, feather, and a straw. Vi enjoyed it, and later Volcano took up the challenge. The marble sometimes rolls out. The straw is good for chewing and pulling. They don’t reach through the holes very much.
Volcano and Velvet started lowest on weight and have been gaining but more slowly than their siblings. I tried pushing extra food at them, out of reach of the others, and after a ho-hum attitude at first, they’ve been pigging out: 20 grams and 30 grams heavier than this morning, which out of 400 grams is fairly significant. Yes, it’s not doing more than being belly ballast at first, but if they eat until full instead of until something else interesting or some pushy sibling takes over, they should gain a little faster.