How Strong Can Carts be Made?

Although mixing cart to a "1:1" (e.g. 0.5g of dimitri dissolved in 0.5ml of PG to form ~0.95ml of total d-juice) is common, it's actually possible to make carts considerably stronger.

Below is a technique provided to us by our trusted friend and Discord member @CrazyDiamond, who has perfected the art of making & using max-strength carts.

Crazy Diamond's 2:1 'Maximum Welly' Tek

Required

A new empty 1ml "510" ceramic cell vape cartridge (e.g a Ccell TH210, get the 2.0mm holes version if there is a choice)
800mg of freebase dimitri, preferably as non-waxy & fluffy as possible
A small amount of PG (propylene glycol) - 0.4ml
1ml glass concentrate syringe
2 x blunt tipped needle (14 ga is ideal)
Cotton buds or 1um 13mm diameter syringe filters
Optional - device to provide gentle heating e.g. mushroom dehydrator
small glass vial (e.g. 3 - 5ml). Shot glasses would suffice at a push

Procedure

Mix 800mg of dimitri with 0.4ml of PG in the vial. It'll seem like an impossibly large amount to dissolve and willform a thick paste at first, but be assured that if you've measured things out correctly it will be fine
Thoroughly stir the paste and then optionally put the vial in a mushroom dehydrator at 150F for about 20-30 minutes, swirling occasionally as needed. If a dehyrator is unavailable then a similar device can be used to provide gentle heat

Note by Minty - I have successfully dissolved a 2:1 mix at room temperature (22°C), although I left it overnight to ensure complete dissolution.

Once the PG/dimitri mix appears dissolved & uniform, continue with heat and stir for at least another 20 minutes
Remove the vial and suck out juice out with the syringe fitted with a blunt tipped needle (no filter fitted)
Then fit the syringe filter or if using a cotton bud filter, swap to a 2nd needle with a wad of cotton in the needle fitting. For more info on using a piece of a cotton bud as a filter see this page, also this point in the Zues video
If double-filtering is desired then inject the juice through the filter back into the vial and draw again. If using a syringe filter, it shouldn't be needed.
Inject the juice through the filter into your cart and secure the mouthpiece

Additional Notes

Just less than 1.2ml of total d-juice will be produced, which is the correct amount to fill a 1ml cart, including an amount that the cart's wick absorbs
Once dissolved, the solution is thick and syrup-like, holding the cart under an armpit or similar for 5 minutes appears to be sufficient to prepare the cart for use.
After the first toke, the cart's ceramic core appears to heat the fluid sufficiently to allow it to resaturate over the next 20-30 seconds whilst holding the hit
If accustomed to lower strength carts, be prepared for stronger effects than expected
2:1 mix is right at the upper limit of solubility and crystallisation can result in storage. This is easily remedied by warming them whilst inverted then rolling them around a little. Take care when applying heat while upright because the juice can seep through the wick and leak from the carts air holes
As always, recommend storing carts inverted to help prevent leaks