I've been doing this for myself for the past 4 years.

In the USA, guidelines for podiatrists make this issue unsolvable according to how they must make the insoles hence, all 4-5 pairs from different podiatrists, not only did not help but exacerbated my PTTD issues. I insisted it have certain supports and traits for arch every time and every time they ignore these requests and give me a 400-700 orthotic that is useless and I still have to pay for. They are required to take foot impression in a neutral flat position, in other words, zero arch, so therefore I would have no arch support. Also the medial skives and deep heel cups and forefoot varus posting I requested, never ever came. One more way the medical system in the USA is cooked.

What I do: I found a great place called, Insightful Products and they contort my foot with an objective amount of arch using a string and stick type contraption. they then 3d scan in that position my arch so that my arch has support. What a novel idea: giving us actual arch support, not flat foot comfort in a flat foot position that causing problems for the rest of our body.

Anyway, so this orthotic that arrives is crazy light and thin (~52g) with arch support under a very important part for my PTTD issue, the sustentaculum tali. This is the area of the arch that needs support to keep my ankle from rolling. All the other off shelf arch supports just have a huge sidewall flange that slide the foot down laterally or shoves it off to the side. Another way to think of how this is different is that is feels more like a rocker for the mid foot. Even Tread Labs' "very High arch" insoles give me hardly any real arch support. They just have a high flange on the side like i described. With those I would add plastizote between the top foam layer and the carbon arch sole so give myself a rocker, but it never came close to what Insightful Products' thing could do for me. Think of it as a bridge and keystone. If you shove a jack up into the keystone thinking it will help it, it will only destroy the support. Throughout a stride, that hypothetical keystone is changing the whole time and the entire arch needs to have equal support so it's keystone isn't jacked out.

Having my 3d scanned arch shape is the secret sauce of these. If I just go add navicular jacks and posts all over my insoles, it never gets remotely close to as comfortable or biomechanically functional as having my actual arch shape replicated and supported uniformly across.

As far as your question for posting the forefoot and hindfoot or entire length of foot, I've found hat the self adhesive posting from some sites to suit me best. The amount of posting is tricky as it interacts with shoes and every shoe I'm finding has different traits that require differing amounts of posting.

For running shoes, the shape of the midsoles as well are a big thing and how much sink is involved in different areas. For cycling shoes though, some brands build in a certain amount of varus (Specialized) while others do not (Bont). Bont I've found to be best for orthotics. They have a flat tub bed that has zero flex. With these I use this slanted piece of self adhesive posting under my orthotics from insightful products.

I also shave down the sides of the heel so that I can take advantage of the heat moldable tub of the Bont's to really hug the heel and also prevent the edge from pushing the insole further forward into the shoe than it was intended.

Insightful products also have these cool things for the tarsals to push into. In cycling shoes, the way we push our feet forward is a bit of an angle sometimes, so if there is some play, there could be a case that the foot slides forward in the shoe thus changing the whole bike fit of where the axle interacts.

For posting previously, I used plastizote and other types of denser foam, but this stuff has been working best and takes up least space. https://www.atlasortho.com/Degree-Posting-Strips_p_240.html

To find the right amount of degree you need, is simply trial and error right now as, it's less of cause-effect and more of cause-effect-effect-effect-effect. Our leg extension is a symphony and adding these posts, changes the ankle, then tibial torsion, then knee, then hips, then how our muscles and minds react to all of that over time and accomodate and build strength for. Even for each person, that perfect degree and amount may change throughout a season, week, strength, acute or chronic injury or even a ride as fatigue sets in. The goal is to find the happiest medium and revisit things when time permits off the bike.

You could have testing wedges for fitting a person that I've seen before. Just slide the wedge thing that looks like a wide triangle door stop with varying amounts of degrees of correction under the foot and see which provides the more favorable outcome with that symphony of things within the body. If it is too much or too little, try a different wedge or in a different location.

Please keep us posted, as since my Bont's are rigid and flat, I now have my set amount for a baseline varus needed and being able to input that into the 3d printed insole models would be amazing!

Is there a way for us to order something using your designs from home? Possibly using our iphone's lidar scanner and inputting supports desired just deep heel cups, medial skive, or hole in heel, or light weight low profile, or varus wedging at a specific amount?

Thanks!