As my daughter gets older (18 months) her legs are so long so it can be awkward to thread her legs through the sling as I hold her against my shoulder. Lately I have been pulling the pouch part of the sling so it is a few inches larger than usual before I put her in, then when her legs are through, I pull on the whole tail so it is the right size again (so her bum will fall at my waist when worn), then I spread the pouch part out and settle her in.
There are several options if you would like to make or purchase a sling to comfortably carry your toddler. Linen and silk are the best fabrics to support the weight of a toddler as they are made from strong fibres. I have found one of the most comfortable and supportive fabrics for a toddler ring sling is a single layer of medium weight linen. A double layer of lightweight linen or medium weight silk is also great, and a combination of silk (medium weight) and linen (light weight) is comfortable (and pretty!). Another option is to use a woven wraparound sling as these are specially woven for wearing babies and have a nice amount of give. The Hipababy gathered shoulder also helps distribute the weight of your toddler across your whole shoulder for comfortable wearing.
I love to sew. I have five curious and active kids who keep me busy!